Semen samples from 500 Nigerian male partners of infertile couples were classified according to their sperm counts and progressive motility. 74.15% of these men were normozoospermic while 16.19, 5.57 and 4.09% were azoospermic, necrozoospermic and asthenozoospermic, respectively. The degree of oligozoospermia was mild (35.88%), severe (23.22%) or very severe (40.90%). The classifications of two consecutive samples per patient collected two weeks apart were highly correlated. Results show that in over 70% of these infertile couples, infertility was due to a female factor, the absence of which therefore has to be established before semen analysis. Some socioeconomic factors in infertility were also implied.