Four balanced autosomal reciprocal translocations were found through mitotic chromosome analysis among 72 subfertile males, 27 with azoospermia and 45 with sperm counts below 40 X 10(6)/ml. They were 46, XY, t(3; 20; 21) with azoospermia, 46, XY, t(14; 21) with sperm counts below 1 X 10(6)/ml, 46, XY, t(1; 19) lqh+ with azoospermia and 46, XY, t(3; 16) with sperm counts 27 X 10(6)/ml. Histological, cytogenetic and hormonal analysis were performed. Testicular biopsies from the first 3 carriers revealed complete spermatogenic arrest at the spermatocyte stage and meiotic studies of the same biopsies showed severe reduction in numbers of cells in 2nd meiotic division. In spite of severely defective spermatogenesis, serum gonadotropins of the carriers were within normal range, except for LH of the 4th case. Other chromosomal aberrations observed were 5 Klinefelter's syndrome, 2 autosomal minor variants (46, XY, 15p+ and 46, XY, 14s+) and 1 small Y.