Objective. To assess the difference between human immunodeficiency virus (HIV)-infected and non-infected tuberculosis patients with regard to demographic characteristics, clinical features, case fatality rates and, particularly, compliance with therapy. Design. Cohort study. Setting; Hlabisa Hospital, KwaZulu-Natal, a 450-bed hospital serving a rural district containing 180 000 people. Patients. Two hundred and ninety-seven consecutive adult patients (> 15 years) diagnosed with tuberculosis. Main outcome measures. Age, sex, type of tuberculosis, case fatality rate and compliance with therapy. Results. A total of 107 out of 297 (36%) adults tested HIV-positive (95% confidence interval (CI) 31-42%). Prevalence of HIV infection was higher in women than men (46% v. 29%, relative risk (RR) 1.6, 95% CI 1.2-2.2). HIV-positive patients were significantly younger than HIV-negative patients (mean age 31.2 years v. 38.7 years; P < 0.001). Extrapulmonary tuberculosis (EPTB) was more common in HIV-positive patients (41% v. 11%, RR 3.7, 95% CI 2.3-5.9). The case fatality rate was higher in HIV-positive patients (13% v. 9%, RR 1.5, 95% CI 0.7-3.0). Many more HIV-positive patients failed to complete treatment (21% v. 7%, RR 3.0, 95% CI 1.5-6.0). Conclusions. We found that HIV-positive patients with tuberculosis were three times more likely to fail to complete treatment than HIV-negative patients. HIV infection is clearly altering the epidemiological profile of tuberculosis in rural South Africa and poses an additional challenge to tuberculosis control programmes to maintain high case-holding rates among HIV-infected tuberculosis patients.