[Methodological approach of a retrospective study on 484 fertile and 2 768 infertile men (author's transl)].

One possible method to study male factors in fertility is the retrospective comparison of groups of fertile and infertile men. Such a study based on 484 fertile and 2 768 infertile men enables us to point out an increasing risk of infertility with decreasing sperm counts and percentage of motile spermatozoa and with increasing abnormal forms. However the increase in relative risk is sharper for the patients who consulted twice or more than those who came for the first time. This difference might in part be explained by the fact that the former had a longer duration of infertility or that the couple infertility had less often a female origin. Consequently detailed information on this subject must be taken into account in studies on fertility.