Two cases of pericentric inversion involving a chromosome no. 10 are reported in infertile men. Using R-, G-, and C-banding techniques, the inversions were identified as inv(10)(p15q11) and inv(10)(p11q21). A similar chromosome was found in a parent of one of the probands. The literature on similar cases is reviewed briefly and the relationship between pericentric inversion and sterility are discussed.