In 1986, the regimen with isoniazid, rifampicin and streptomycin or ethambutol for 9 or 6 months was introduced as the standard therapy for the initial treatment of pulmonary tuberculosis in Japan. Since then, several reports have been published on the relapse rate after such standard regimen, but follow-up observation was limited to relatively short period in these studies, except one study. Further, none of these studies reported overall efficacy rate of the treatment which was the most important index to evaluate the regimen. So we investigated the deaths, defaults, treatment failures, and relapses during and after the initial treatment of pulmonary tuberculosis patients to calculate the efficacy rate. Three hundred and six patients with newly diagnosed pulmonary tuberculosis, who had admitted to Fukujuji Hospital and started initial treatment with standard regimen, were followed-up, retrospectively. At the start of the initial treatment, mean age of the male patients were 47.0 and those of the female patients were 42.2 years old (male: 232 cases, female: 74 cases). Of the total 306 patients, 84.5% were basically positive and 50.7% were cavitary tuberculosis. Resistance to isoniazid, rifampicin, streptomycin and ethambutol was noticed in 3.5%, 0.4%, 4.3% and 0.4% of the patients tested. Their medical records in Fukujuji Hospital were reviewed, and for the patients who had not visited the hospital more than one year letters were sent to request to visit the hospital and to answer to questionnaire. The questionnaire were also sent to the referred hospitals and the concerned health-centers. Of 306 patients enrolled in the present investigation, 7 have dropped out.(ABSTRACT TRUNCATED AT 250 WORDS)