This is a report on 912 patients treated during 1973 to 1979 for pulmonary tuberculosis and/or extrapulmonary organ involvement. These patients had been treated with a fixed tablet combination of isoniacide, prothionamide and diaphenyl sulfone in association with rifampicin and partly other substances. It was the aim of our study to examine this form of therapy in respect of side effects and effectivity. 535 of these 912 patients were followed up for as long as 13 years (maximum follow-up period). According to the criteria of the American Tuberculosis and Respiratory Diseases Association the patients were suffering from 182 cases of pulmonary tuberculosis of only slight extension, 490 of moderate extension and 130 of large extension, as well as 55 cases of pleuritis, 67 extrapulmonary organ tuberculoses and 1 tuberculosis of the bronchial mucosa. Allergic skin reactions occurred in 0.7% of the cases, and in 0.9% there were neurological disturbances such as vertigo, paroxysms and polyneuropathies. In 7.4% of the patients there was an increase in serum enzyme activities of SGOT, SGPT, Y-GT as a sign of hepatotoxicity. In 5.5% of the patients there were several gastrointestinal concomitant phenomena such as sensation of fullness, nausea, and vomiting. Under IPD therapy the hemoglobin valuedropped on the average by 12% up to the 5th or 6th week of treatment and rose subsequently to almost normal levels. No permanent damage was seen in any of the patients under observation. In the moderately extended tuberculosis cases disinfection occurred on the average between the 6th and 8th week of treatment, in the greatly extended cases on the average in the 9th to 13th week.(ABSTRACT TRUNCATED AT 250 WORDS)