Objective To compare the efficacy, toxicity and later period complications of Cf-252 neutron intracavitary brachytherapy(IBT) combined with external-beam radiotherapy (EBRT) with those of EBRT alone in patients with esophageal carcinoma. Methods Eighty-six patients were randomized into 252Cf neutron IBT and EBRT group (intracavitary group: 43 patients) and EBRT alone group (external group:43 patients). The external group was treated with three-dimensional conformal radiotherapy(3DCRT) or conventional radiotherapy of 70 Gy in 7.0 weeks using Elekta Precise medical linear accelerator. The EBRT in intraeavitary group was as same as external group, except the total dose was decreased to 60 Gy in 6.5 weeks. For IBT, the applicator with special water bursa was settled to the esophageal lesion through the mouth. The dose calculation point was 10 mm far away from the source and 1-2 em cranial-caudally from the tumor margin. 252Cf braehytherapy was delivered 3-4 fractions at 4 Gy per fraction per week. In intracavitary group, EBRT was begun on the second day of IBT. EBRT and IBT were not given on the same day. Results After the treatment,the esophageal stricture was relieved earlier in intracavitary group than external group.Six patients in intracavitary group who had drinking obstruction symptom could eat liquid food after esophageal balloon dilation, one fraction of 252 Cf neutron IBT and 5-6 days of EBRT, and could eat semiliquid food two weeks after. In the third month, the complete response rate, partial response rate and no response rate were 33%, 67% and 0% in i ntracavitary group and 19% ,76% and 5% in external group, respectively. The overall response rates of the two groups were 100% and 95% ( χ2 = 4.32, P ＜ 0.05 ). The 1 -year local control rates were 84% and 70% (χ2 =4.57 ,P ＜0.05). The 1-year survival rates were 81% and 61% (χ2 =4.17,P ＜0.05 ). The rates of acute esophageal toxicity was 61% and 51% ( χ2 = 1.75,P ＞ 0.05 ). The acute radiation esophagitis was slightly higher in "BZ ]intracavitary group than that in external group, but the difference was insignificant. The late esophageal-cardiac stricture had no significant difference between the two groups. Conclusions 252 Cf-252 neutron IBT plus EBRT, without increasing the toxicity,are better than EBRT alone.