Sera from 170 factory workers aged 18–45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti- Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti- Toxoplasma antibodies was 80·0% (95% confidence interval 73·9–86·1%). The sensitivity and specificity of the Eiken latex agglutination test were 96·3% and 97·1%, respectively, showing its validity for the detection of anti- Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74·2% versus 83·3%, P>0·05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected ( P < 0·001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti- Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.