TB Treatment Centre, Kampala, Uganda.To evaluate the impact of human immunodeficiency virus (HIV) co-infection on the bacteriologic and radiographic presentation of pulmonary tuberculosis (TB) in Uganda, a nation with high rates of Mycobacterium tuberculosis and HIV infection.To compare baseline characteristics among HIV-infected and non-HIV-infected adults with initial newly-diagnosed episodes of culture-confirmed pulmonary TB screened for participation in a randomized prospective TB treatment trial.Negative and paucibacillary (very scanty or scanty) sputum acid fast bacilli (AFB) smears were more frequent in HIV-infected patients presenting with pulmonary TB (P = 0.007). More HIV-infected individuals also had sputum cultures that required 7-8 weeks incubation until positivity than non-HIV-infected patients (P < 0.01). Lower lung field and diffuse pulmonary infiltrates were more frequent among HIV-infected patients. Rates of atypical X-ray presentations and cavitary disease were comparable between HIV-seropositive and -seronegative patients; however, atypical disease was more frequent in HIV-infected patients with small tuberculin reactions or tuberculin anergy (PPD = 0 mm).HIV co-infection was associated with a higher frequency of negative and paucibacillary sputum AFB smears. The differences in the diagnostic yields of microscopy and culture between HIV-infected and non-HIV-infected individuals were small and do not, in our opinion, significantly affect the utility of these important diagnostic tests in developing countries. Examining more than one sputum specimen and monitoring cultured specimens for a full 8 weeks may assist in optimizing the diagnostic yield. Upper lobe infiltrates and cavitary disease are still the most frequent radiographic presentations of pulmonary TB in HIV-infected and non-HIV-infected adults in countries with a high prevalence of TB.