Abstract: Objective :To assess the effects of prophylactic cranial irradiation(PCI) on thesurvival and brain metastastic rates in patients with limited-stage small-cell lung cancer (SCLC)in complete remission. Meth-ods : Thirty patients with limited-stage SCLC in complete remissionafter operation with chemotherapy or the patients with unresectable SCLC combined with chemo-radiotherapy were randomly divided into PCI group (n=30) and control group (n=40) from June1990-july 1995, male 22 and female 8.The pathologic stages were I 8、II 15 and III a 7.The chemotherapy protocol: CAE (C: cyclophosphamide; A: adriamycin; E: etoposide) or EP(E: etopo-side; P: cisplatin). For CPI group, 30 patients were given to a dose of 30 Gy/15 times by 1.8-2.0 Gy per fraction, forty comparable patients(control group), male 28,female I 2, I10, II 20 and111 a 10 ,were treated with chemotherapy after surgery or the patients with unresectable SCLC combined with chemo-radiotherapy without CPI. Results : The incidence of cranial metastasis inCPI group was 10.0% and in the control group was 52.5%,there was greatly significant differ-ence between two groups (X²=13.73, P<0.001).The 1-3-and 5-year survival rates of the CPI group were83.3%, 60.0% and 20.0%, respectively. 1-3-and 5-year survival rates of the control group were80.0%, 47.5% and 15.0% respectively, the 5-year survival rates of the PCI group and the control group in I、II、Ⅲ_A、stake were60.0%,42.9% and 25.0%; 55.6%,38.5% and 10.0%,able to decrease the lneldenee of cranial metastasis and whether the survival rate can be im-proved or not, this result may not be conelusive due to the limited numbers of patients studied.