Tuberculosis is an important infection encountered after renal transplantation in third-world countries. Over an 8-year period, 36 cases of tuberculosis were encountered in 305 renal transplant recipients (11.8%) with grafts functioning for more than 3 months followed up at our center. The infection was limited to the thoracic cavity in 41.7% and a single extrapulmonary site in 11.1%, and it was disseminated in 27.8% cases. In 19.4% of cases, the disease appeared as pyrexia of unknown etiology and the diagnosis was confirmed by a good therapeutic response to antitubercular therapy. Tuberculosis was diagnosed within 1 year of transplantation in 58.3% of cases. There was no significant difference in the incidence of tuberculosis in patients on different immunosuppressive regimens. The Mantoux test was positive in 33.3% patients. A total of 23 patients were treated with isoniazid and rifampicin, with the addition of a third drug for the first 2 months. Treatment was continued for 9 months in 11 cases with isolated pleuropulmonary disease and for 12-15 months in the other 12 patients. The other 13 were on cyclosporine and were given isoniazid, pyrazinamide, and ethambutol for 18 months. Two patients died of fulminant disease and five more died from unrelated causes. No recurrence of disease has been noted in any of the patients after a mean follow-up of 14.6 months. We conclude that the incidence of tuberculosis in renal allograft recipients in third world countries is much higher than that seen in the western world. Most of the cases are encountered in the first posttransplant year. Tuberculosis must be considered seriously in all patients who have prolonged fever of undetermined etiology. Treatment with isoniazid and rifampicin for 9 months is adequate for patients with localized pleuropulmonary disease. In patients on cyclosporine to whom rifampicin cannot be given because of economic considerations, treatment with isoniazid, pyrazinamide, and ethambutol should be given for 18 months.