The purpose of this article is to examine the relationship between availability, prices of medicinal products and public health interests. To this end, we used a methodology for analysing the economic interests involved and also a systematic method of processing existing national, Community and international legislation. We have also used legal methodologies compared between our national legal systems and those of other western countries. There is a close link between the availability and prices of medicines and public health interests. Our current legal system recognises inventors of new medicines as a “monopoly” to negotiate on the pharmaceutical market. To protect our public interests Regulation sets some limits to the rights of inventors. Property rights are limited in time and under some circumstances it is mandatory to authorise others to use the patent under a licensing agreement. The World Trade Organisation it has established (WTO Council Decision, Doha Round 2003) further limits to these duties in case of exceptional conditions. Our National Constitution gives precedence to public interests over private interests. It is a duty of governments to establish a fair system in which inventors can get an economic reward for their creations and society can meet their health needs.