We have typed 9 EBV cell lines from azoospermic or severely oligospermic patients for the expression of H-Y antigen, in order to test the hypothesis of the coincidence of AZF and HYA genes. Of nine patients with cytogenetically normal Y chromosomes, 7 could be tested for HYA expression and of these 6 were H-Y positive. Of the three patients showing Yq structural abnormalities, two could be tested for H-Y expression and one was negative, the other positive. These results therefore show no correlation between spermatogenic failure and the absence of HYA, thus separating the AZF locus from HYA.