Introduction The role of religion and its influence on different aspects of social life has always been under the attention of sociologists of religion but gender differences, its reasons and factors, have often been overlooked. Even research on this subject sometimes leads to inconsistent results. Generally, such research shows that women outdo men in prayers, religious activities and religious beliefs. There are so many different opinions about the reasons of such differences. Some attribute it to position structure, some to gender orientations and gender socialization, some to personal differences and some to the theory of risk aversion. Therefore, given the importance of the subject, little available research about it, and different, sometimes contradictory findings, it is essential to study the role of gender in religiosity, addressing questions such as: are women and men equally religious in our society? Are there any differences between women and men in terms of religiosity? Does research on different religions confirm these findings? Can power structure in family explains women’s greater religiosity? The present study attempts to answer these questions. Despite different research that shows women outdo men in prayers, religious activities and religious beliefs, Lowenthal believes that these differences depend on the culture and tradition of each religion. He states that any religion differentiates between religious obligations of men and women. Islam and Judaism, for example, place less strenuous duties upon women than upon men. In Judaism, women are not required to pray with a congregation and in Islam women should not enter mosques during their menstruation. Therefore, women are expected to pay less attention to the place of worship and to take part in some religious activities less often than men. In Christianity and Hinduism, in contrast, women are more religiously active than men. Hindu women are more willing to go to temples and probably Muslim and Jewish men do more religious activity than women and this is in contrast to Christians and Hindus. Loewenthal suggests that such differences lead us to expect different gender effects between Christians, Muslims and Jews. He concludes that although women are more religious than men, they do less religious activities than men do. In Christianity, women are more religious than men. In Hinduism, Islam and Judaism, men are more religious than women. Lowenthal attributes such differences to traditions and cultural norms of religions, whereby he negates this general principle that women are more religious than men (Loewenthal, 2001). To justify reasons of such differences, Miller and Stark believe that such gender differences have a physiological origin, resulting from risk priority. They suggest that men show more risky behaviors because of their risk priority and women are more religious due to their physiological nature of risk aversion. Extending the control-power theory of Hagan and colleagues and accepting risk-priority theory of Miller and Stark, Collet believes that these differences have a social origin, whereby gender differences in religiosity is linked to power structure of family and is thus explained. He states that boys in patriarchal families are encouraged to show more risky behaviors and girls are restricted to do so. Such gender differences seem to be lesser in egalitarian families. According to this theory, patriarchal or egalitarian families, by showing different behaviors, cause different gender socializations in children, which continue until adulthood. Since girls in patriarchal families are controlled more than girls in egalitarian families, they show risk aversion more and therefore are more religious. In view of the theoretical approaches of this research, which are based on the opinions of Loewenthal and Collet, we examine the following assumptions: women are more religious than men; religiosity is not equal in different religions; women living in patriarchal families adhere to religious values and are more religious. Materials & Methods The present study is a national survey research which has been carried out by means of questionnaire and multistage cluster sampling. The research data are based on the findings of the project for studying global values. Statistical population of the research consists of all people above the age of 16 in Iran, who were chosen by using Cochran Formula with a sample volume of 2275. Variables of religiosity, fathers' influence and patriarchy were conceptualized and operationalized and then used in testing research's assumptions by such measures as Cramer’s V and phi. Discussion of Results & Conclusion According to findings of the research, women are significantly more religious than men in all components of religiosity, including; religious values, religious beliefs, personal religious duties, religious consequences, thinking about meaning of life, prayer to God in addition to religious practices and belief in peacefulness of religion. In Iran, there are gender differences in religiosity and it can be said that women are more religious than men. Therefore, the first assumption (women are more religious than men) is confirmed. The only exception is that men take part in religious rituals more than women, but not in a significant level. This also verifies Loewenthal’s assertion that women do less religious activity than men do. Also, gender differences are not equal among Iranian Shias, Sunnis and Christians. The differences among Sunnis are more than among Shias, being in favor of women in both sects. But there is no gender difference among Christians. Therefore, the second assumption which, based on Loewenthal’s theory, asserts that gender differences in religiosity is culture-specific and vary among Christians, Muslims and Jews, is accepted. Loewenthal asserts that women take part in religious activities less than men. This is confirmed with regard to Shias and Sunnis, but not with regard to Christians. He also asserts that Muslim women are less religious than Muslim men, which is not acceptable according to the findings of this research. As mentioned before, Collet link gender differences to the power structure of family, asserting that girls who have been raised in patriarchal families have higher risk aversion and therefore are more religious. According to the findings of this research, however, these assumptions are not statistically acceptable. Therefore, the assertion that religiousness of women depends on the type of family (patriarchal or egalitarian) is rejected. The third assumption which, based on Collet theory, asserts that women in patriarchal families are more religious is rejected. These findings are highly important in view of sociological theory, because in the contemporary world in which power structure in most societies, including Iran, proceeds towards egalitarianism (Inglehart, 1993), (Azadarmaki, 2010), the rejection of this relation may denote the emergence of new structures in families and the possibility to preserve religious inclinations at the same time. The fact is that that acceptance of egalitarianism by families does not necessarily mean a reduction in religiosity. Considering gender studies which often emphasize discrimination against women due to social backgrounds and their inequality with men in some social aspects, studies such as the present one, which shows that gender differences are in favor of women, can have a positive effect on women. Their awareness about such abilities can help them play a more efficient role in their family and in their society, whereby improving their living standards and develop a better generation. In view of the importance of the subject, it is recommended that quantitative and qualitative studies to be conducted on gender differences in religiosity, its reasons and its contributing factors.