Sera of inhabitants of Angola village in central Sudan were investigated for the prevalence of antibodies to Chlamydia trachomatis, C. pneumoniae, and C. psittaci by the microimmunofluorescence (MIF) test. Clinical examination of 616 persons showed that the village is hyperendemic for trachoma. Of the 448 children examined, 334 (75%) had signs of active trachoma. The corresponding prevalence in the 168 adults was 25%. Using MIF, antibodies to C. trachomatis were found in the sera of 27 (81%) children and of 37 (88%) adults with trachoma. Antibodies to C. pneumoniae occurred in 13% and 24% of the preschool and school trachomatous children, respectively, and in 64% of the adults, which reflects earlier exposure to C. pneumonia in the Sudan than generally reported from temperate zones. Antibodies to C. psittaci were found in 6% of the children less than 16 years old and in 17% of the adults. Of the patients with trachoma, 16% had antibodies to both C. trachomatis and C. pneumoniae. The prevalence of multiple antibodies to Chlamydia increased with age. Antibodies to all three species occurred in 3% of the patients. The study does not support the existence of protective immunity between C. pneumoniae, C. trachomatis, and C. psittaci, as shown by the high prevalence of chlamydial antibodies in the hyperendemic trachoma community studied.