Even though workplaces have undergone several transformations in recent decades, employers are constantly looking for flexibility, which has particularly impacted employment status and working time. These changes had the effect of raising the issue of work/life balance (WLB) at the heart of discussions. Although there has been progress in the labor market regarding WLB in recent years, some issues remain. The main one being the incompatibility between the professional and family spheres which can have negative repercussions. This research will examine the effects of union presence on access to WLB measures and their perceived effectiveness by human resources professionals. This quantitative study is based on data collected by Émilie Genin and Mélanie Laroche, professors at the School of Industrial Relations of the University of Montreal between 2017 and 2018. The data was collected in partnership with the Ordre des conseillers en ressources humaines et relations industrielles agréés du Québec (CRHA). Our data is constituted by a sampling of 249 respondents. The research hypotheses were tested using data collected from human resources or industrial relations professionals, members of the Ordre des CRHA du Québec. In this research, we sought to understand whether unionization has an effect on the number of WLB measures offered in the workplace and whether unionization has a moderating effect on the relationship between WLB measures and their perceived effectiveness. Our model allows us to make various findings. Research results show that unionization has no effect on the number of WLB measures offered in organizations. A positive relationship was also observed between the number of WLB measures and their perceived effectiveness by human resources professionals. Finally, our results show that unionization does not have a moderating relationship on the presence of WLB measures and their perceived effectiveness. We aimed to contribute to the literature by focusing on the effect of union presence on access to WLB measures and their perceived effectiveness. While little research specifically examines these elements, our study allows for reflection on the impact of union presence on the WLB. This study also serves as a reference for all employers, unions and governments who wish to shed some light on the issue of WLB.