In the last 50-60 years, has been observed a significant decrease in human fertility which affects 10% of couples. Although infertility is often attributed to female cause, a male factor is solely responsible in about 20% of infertile couples and contributing in another 40-50% of cases. The purpose of the present study was to evaluate the causes of infertility to men at reproductive age. Material – method: The sample study included 106 infertility married men that seeked medical help in a Centre for Reproductive Health. Data were collected by the completion of a specially designed questionnaire for the needs of the research which included both demographic data and questions about the causes of infertility. Results: From the 106 men οf the studied population, 56,6% were men 30-39 years old, 27,4% 40-49 years old,9,4% 50 and above years old and the 6,6% 20-29 years old. The results revealed that oligospermia was the first cause of infertility in approximately 19,8% of men, and the second cause was astenozoospermia in 17,0% of men. «Unexplained infertility» was responsible for another 10,4 % of cases, varicocele was identified in approximately 4,7% of cases and azoospermia was identified in the 3,8% of infertile men. Conclusions: The main causes of men infertility were oligospermia, astenozoospermia unexplained infertility, varicocele and azoospermia. It is important, an educational – informing strategy towards men population to be adopted, which will improve knowledge about the causes of an impaired male fecundity and will significantly contribute to the solution of the problem.