Abstract: Objective: To explore the result and side effect of the 3 dimensional conformal radia-tion therapy (3DCRT) for primary liver cancer.Methods: From Mar. 1997 to Oct. 2000, 89 patientswith primary liver cancer were treated with 3DCRT. Radiotherapy was designed by 3- D treatment plansystem of the Elekta company. Dose volume histography (DVH) was used to verify and optimize the ra-dio- therapeutic regimen. The total dose was 40 Gy and it was delivered 4-5Gy per fraction, once everyother day, with total 8-10 fractions during 16-20 days, using 5-6 coplane or non- coplane for conformalirradiation. The immediate response and side effect were evaluated based on the WHO and RTOG cri-terion system.Results: Three months after irradiation, the overall immediate response rate (CR+PR)was 78.7%. The 1-, 2-and 3-year survival rate were 64.0%(57/89), 41.6%(37/89) and 28.1%(25/89),respectively. The immediate response was related to the target volume. The smaller the targeted volume,the better the response (χ²=18.428, P=0.005). The side effect of acute irradiation was mainly digestivetract effect and radiation-induced liver injury. The radiation- induced liver injury was also related tothe radiated volume of the liver.Conclusions: Three dimensional conformal radiotherapy can be con-sidered as an effective and feasible approach for primary liver cancer, with no any serious complica-tions.