The prevalence of Toxoplasma dye-test antibody was determined in inhabitants of a number of Pacific islands, in Melanesia, Micronesia and Polynesia, and on Taiwan. With the exception of one island in French Polynesia, two Hawaiian islands, and Taiwan, Toxoplasma antibody prevalences were high, ranging between 84% and 100% in the adult populations tested. On the Hawaiian islands of Oahu and Hawaii, populated by several ethnic groups, and where about 50% of the total adult populations were estimated to have been infected with Toxoplasma gondii, a marked variation in prevalence of infection by ethnic group was observed. The lowest prevalence in the Hawaiian islands estimated at about 15% to 20% in adults, was observed in Japanese. On Taiwan, only 6% of adult ethnic Chinese and 1% of aborigines tested had Toxoplasma antibody.