SUMMARY A total of 494 patients (90 men and 404 women) attending a sexually transmitted diseases (STDs) clinic in Khartoum, Sudan, were-studied to assess the prevalence of chlamydial genital infections. Antibodies to Chiamydia trachomatis serotypes D to K were found in four (4' 4%) men and 42 (10-4%) women, and 10 (2 5%) women had antibodies to serotypes A to C.