ABSTRACT External radiation measurements were made at several atolls in the northern Marshall Islands, which are known or suspected to have been the recipients of tropospheric fallour during the Pacific Testing Programs. Surficienct data were available co ascertain realistic dose predictions for the inhabitants of Rongelap and Utirik Atolls where the 30 year inregral doses from external sources exclusive of background radiation were 0.65 and 0.06 rem respectively. These estimates are based on realistic lifestyle models based on observations of each atoll community. Ailuk and Wotie Atolls were found to be representatives of regional dackground radiazion levels,