PURPOSE: To assess the efficacy of high dose rate - intracavitary radiotherapy (HDR-ICR) in the radiotherapy of FIGO stage IB squamous cell carcinoma of uterine cervix and to determine the optimum dose combination xheme of external radiotherapy and ICR to achieve acceptable local control without severe complication. METHODS AND MATERIALS: One hundred and sixty two patients with FIGO stage Ib squamous cell carcinoma of uterine cervix who received definitive radiotherapy between May 1979 and December 1990 were retrospectively analyzed. All the patients received external radiotherapy combined with HDR-ICR. External dose of 40-46 Gy in 4.5-5 weeks was given to whole pelvis(median 45 Gy) and ICR dose of 30-39 Gy in 10-13 times was given to the point A. Midline shielding was done after 20-45 Gy of external radiotherapy(median 40 Gy). Summation of external dose plus ICR dose to the point A range were 64.20-95.00 Gy, and mean was 83.94 Gy. We analyzed the local control rate, survival rate, and late complication rate. RESULTS: Initial complete response rate was 99.4% for all patients. Overall 5-year survival rate was 91.1% and 5-year disease free survival rate was 90.9%. Local failure rate was 4.9% and distant failure rate was 4.3% Tumor size was the only significant prognostic factor. When tumor size greater than 3cm, 5-year survival rate was 92.6% and less than 3cm, that was 79.6%, Late complication rate was 23.5% with 18.5% of rectal complication and 4.9% of bladder complication. Mean rectal dose summation of external midline dose plus ICR rectal point dose was lower in the patients without rectal complication(74.88 Gy) than those with rectal complication (78.87 Gy). Complication rate was inceased with low rate of improvement of survival rate when summation of external midline dose plus point A or point R dose by ICR was greater than 70-75 Gy. CONCLUSION: The definitive radiation therapy using high dose rate ICR in FIGO stage IB uterine cervical cancer is effective treatment modality with good local control and survival rate without severe complication.