The application of radioactive tracers for placental localization has been introduced as the worth whilediagnostic method in placenta previa. Recently 113m In has been applied as the broad spectrum agent for thevisualization of various organs. The advantages of 113m In are a short half-life with 1.7 hours and no betaparticle emission. During the period from May 1970 to August 1971, the placental scanning with 113m In was carriedout at Yonsei Medical Center on 19 cases of Korean pregnant females who had painless vaginal bleeding withsuspicious placenta previa or other placental lesions, clinically. Followings are the results of placentalscanning with Indium-113m. 1) Eight cases out of 19 cases were suggeted as placenta previa and the remaining 11cases were turned out to be normal placental location. 2) Among these 8 cases of positive scanning, placentaprevia totalis was 6 cases, placenta previa partialis was 1 case and placenta previa marginalis was also 1 case.3) Among 11 cases of normal placental localization, right side placenta was 7 cases and left side, 4 cases. Theplacental scanning with indium-113m is thought to be one of the simple, safe and rapid method with high accuracyfor clinical diagnosis of the placenta previa and placental localization.