Abstract: Objective 　To observe the curative effects of external irradiation ( EI) combined with californium-252 (²⁵² Cf) neut ron int raluminal brachytherapy ( IBT) for t reatment of rectal carcinoma. Methods From May 2001 to May 2004, 30 cases of rectal carcinoma were treated with ²⁵² Cf neut ron IBT, 5 Gy/fraction/ week, the total dose of IBT was 20 Gy/ 4 f ractions. From the second day af ter ²⁵² Cf neut ron IBT, ⁶⁰ Co EI was delivered at 2 Gy per fraction, 4 times per week, the total dose of EI was 45～50 Gy. Results ① After irradiation, 87. 5 % blood stool disappeared completely, 12. 5 % reduced distinctly ; 76. 5 % abdominal pain complete remission, 12. 5 % distinct remission, 5. 9 % remission ; ② The short-term curative effect s showed that CR was 26. 6 %, PR was 36. 7 %, SD was 30 %, PD was 6. 6 %; ③ The 1～4 year survival rate was 100 %, 71. 4 %, 46. 6 % and 7. 78 % respectively ; ④ The degree of acute radiation injury showed that, grade 1 and grade 2 of rectum injury were 60 % and 20 % respectively, grade 1 of bladder injury was 10 %; grade 1 of late radiation rectum injury was 20 %. Conclusion 　EI combined with ²⁵² Cf neut ron IBT for treatment of rectal carcinoma, which has distinct improvement of symptoms and slight radiation complications, maybe has good prospect s to use.