' ABSTRACT Radiochemical separations were made by ion-exchange and precipitation techniques and by gamma spectrum analyses to determine the levels of tungsten-185 on selected samples from the Eniwetok and Bikini test site and from the nearby atolls of Rongelap and Ujelang The isotope was identified by its half life, maximum beta energy and gamma energy. High levels of wi85 were found on plant-leaf and soil samples at Belle and Janet Islands (Eniwetok Atoll) and on plankton collected 155 miles northwest of Eniwetok Atoll during August 1958. Lower levels were found at Vera, Keith, and Henry Islands (Eniwetok Atoll), Nan Island (Bikini Atoll), on the | plankton near Ujelang and Rongelap Atolls and on samples from the latter atolls. The wi85 appeared to occur as surface contamination with the exception of one fish sample taken at Eniwetok Atoll in which the isotope was found in the liver and spleen.