Allotypes were determined in 121 cases of smear-positive pulmonary tuberculosis and 33 healthy controls from Indonesia. It was found that the occurrence of Km1 was significantly lower in patients than in controls (p = 0.011), and that phenotypes lacking G1m (17) and G3m(21) as well as Km1 occurred much more frequently among patients than controls (p = 0.0025). Some evidence for an allotypic influence on the antibody response to mycobacterial antigens was found. A lack of G1m(17) or G3m(21) was associated with increased antibody levels in the IgG2 subclass in control subjects and a lack of Km1 with decreased antibody levels in the IgG4 subclass in patients.