Objective To evaluate the feasibility of increasing the perfraction dose in treatment of neoplasms by 3DCRT (three- dimention confornial radiation therapy). Methods From May 1998 to June 2002, the radiation therapy plans of 300 out- cranial neoplasms patients were analysed retrospectively, including 143 patients with chest neoplasms and 157 patients with abdomen neoplasms. The PTV was 7.0 ~ 1 478 cm3, major PTV was encircled by 90 % isodose curve, minor 95 % PTV were encircled by 80 % isodose curve. Prescription dose was 90 % reference point dose, perfraction dose was 5 ~ 10 Gy, a majority of dose was 6 ~ 8 Gy, period of treatment was 5 ~ 15 days with an interval of 0 ~ 1 day. The general dose was given to radical cure dose or appeasement dose. The biological effect increased 10 % ~ 30 %. Results All treatment plans were accomplished and there were not complication which reduced patients' QOL. Conclusions 1.Owing to the f factor, increasing dose of perfraction, shortening general period of treatment and improving radiative biological effect were possible during the 3DCRT. 2. It was suggested that the larger out- cranial neoplasms should be treated by 3DCRT firstly, but precise plan, precise design and precise treatment can not intensely be pursued because of the limit of knowledge. 3. During the 3DCRT for out- cranial neoplasms, 2 ~ 3 times routine radiation therapy dose was secure, credible and effective according to different purpose.