Although standard chemotherapy for initial treatment of pulmonary tuberculosis has been established, regimens for retreatment of tuberculosis have not yet been established. One hundred fifty nine retreatment pulmonary tuberculosis cases admitted to Fukujuji Hospital were retrospectively analyzed. Regardless of the age at the start of retreatment, majority of cases were treated previously between 1955 and 1960. Bacillary negative conversion rate, duration of chemotherapy, follow-up period and bacteriological relapse rate were compared according to resistance against isoniazid and/or rifampicin. Sixty four cases were sensitive to both INH and RFP. For this group the average duration of chemotherapy was 14.6 months, mean follow up period was 47.3 months and relapse rate was 3.1%. This rate was similar to that of initial treatment cases. Sixty one (94%), were treated with more than two sensitive drugs containing INH and RFP. The 22 INH-resistant and RFP-susceptible cases were treated for 18.6 months and followed up for 55.2 months. The relapse rate of this group was 13.6%. Thirteen cases were treated with more than 2 sensitive drugs containing RFP. Eleven cases were resistant to both INH and RFP. Five of them were surgically operated of which 3 cases were converted to negative and among the nonsurgical cases in this group only one remained sputum positive. All of these retreatment regimens did not contain pyrazinamide and ofloxacin. Although bacillary positive rate of INH and RFP susceptible cases was 13.0% at 6 months after treatment and 5.3% at 12 months after treatment, that of INH resistant and RFP susceptible cases were 25.0% and 12.5%, respectively. A certain rule of retreatment could be obtained from the result of this study.