Chromosomal anomalies may be a reason for male infertility. To find out whether this is true mitotic chromosome studies were performed on 41 males with azoospermia and 61 males with oligozoospermia. A constitutional chromosomal abnormality was diagnosed in 14 (34.1%) azoospermic patients and in 2 (3.3%) oligozoospermic patients. The 47,XXY karyotype was the commonest in the azoospermic group. An overall incidence of 15.7% abnormality indicates that routine chromosome analysis of infertile men should be considered.