['The phenotypic effects of the gr/gr partial azoospermia factor c deletion vary geographically and to our knowledge have not been reported in the American population. We evaluated the clinical characteristics of infertile American men with the gr/gr deletion.', 'We retrospectively reviewed clinical data on 1,410 infertile men tested for the gr/gr deletion. We analyzed sperm concentration and the outcome of microdissection testicular sperm extraction with respect to gr/gr status.', 'We identified 73 men with gr/gr deletions, including 43 of 989 (4.3%) with azoospermia, 18 of 317 (5.7%) with severe oligospermia (less than 5 million sperm per ml), 6 of 61 (9.8%) with oligospermia (5 to less than 20 million sperm per ml) and 6 of 43 (14%) infertile men with normospermia (greater than 20 million sperm per ml). A gr/gr deletion correlated with higher sperm production. The gr/gr deletion rate was higher in men with normospermia than in those with a sperm concentration of less than 20 million and less than 5 million per ml (p = 0.021 and 0.006, respectively). Microdissection testicular sperm extraction was done in 22 azoospermic men with gr/gr deletions and sperm were retrieved in 14 (64%). This retrieval rate was similar to that at our center in men with idiopathic nonobstructive azoospermia (p = 0.13).'] Does diagnosis of the gr/gr Y chromosome microdeletion help in the treatment of infertile American men?