METHODS Phnom Penh, Cambodia. OBJECTIVE To determine the burden of active pulmonary tuberculosis among an HIV-infected cohort and the proportion of drug-resistant strains, using active case-finding adapted to a home care setting. METHODS Cross-sectional study. Measures include the prevalence of culture-confirmed Mycobacterium tuberculosis, utilizing a single spot sputum specimen; the proportion of pulmonary TB, detected and undetected; proportion of cases resistant to isoniazid, rifampicin, ethambutol, streptomycin; and the diagnostic value of symptoms. RESULTS Of 441 persons surveyed, 41 (9%) had active pulmonary TB by culture; 29 were smear-positive (71%), and only one case was on treatment. The total burden of pulmonary TB was 12% (54/441), with a ratio of undetected to detected cases of 3:1. Primary isoniazid resistance was detected in six new cases (15%); no MDR-TB was identified. Symptoms were not predictive of active pulmonary disease. Mortality was high among those not surveyed (20%) and those found to have TB (49%). CONCLUSIONS Tuberculosis is epidemic in this HIV-infected population. Active case-finding yielded three times the number of cases already detected and should be considered where resources allow. However, effective passive case detection and improved coordination of TB and HIV care programs are required to address HIV-associated TB morbidity and mortality.