In rural Haiti we measured and compared the muscle protein and calorie reserves (anthropometrics) as well as the visceral protein reserves (serum albumin, tuberculin sensitivity) in 56 HIV (human immunodeficiency virus type-1) seropositive and 108 HIV seronegative pulmonary tuberculosis patients. Results in patients were also compared to the results of the same measurements made in 160 age, sex and residence matched HIV seronegative controls without tuberculosis. Tuberculosis patients, regardless of HIV status, had significantly reduced muscle protein and calorie reserves compared to controls. The serum albumin was significantly lower in HIV seropositive tuberculosis patients (21.0 g/l) compared to HIV seronegative tuberculosis patients (26.9 g/l) and the serum albumin in both tuberculosis groups was significantly lower than in controls (41.3 g/l). The lower the serum albumin in the tuberculosis patients the greater the likelihood of a negative tuberculin test. HIV seropositive tuberculosis patients were significantly more likely to be tuberculin negative than HIV seronegative tuberculosis patients. Tuberculosis is associated with significant malnutrition. Worse malnutrition in tuberculosis patients co-infected with HIV suggests that the effect of the two pathogens on nutrition is additive or, alternatively, that tuberculosis patients who are particularly malnourished are at increased risk for HIV.