OBJECTIVE We sought clues to the etiology of ovarian cancer by comparing the incidence rates among Chinese, Japanese, and Filipino migrants to the United States and among their descendants with rates among U.S.-born whites. METHODS Information on age, race, and birthplace was obtained for each resident of Hawaii, San Francisco/Oakland, and western Washington identified by the Surveillance, Epidemiology, and End Results (SEER) cancer registry operating in each of those areas with incident ovarian cancer diagnosed during the period from 1973 to 1986. The number of women-years at risk was estimated from a special tabulation of the 1980 census. RESULTS Among U.S. residents aged 20-79 years, the annual incidence of epithelial ovarian cancer among U.S.-born women of Asian descent was nearly the same as that of women born in Asia (respective annual rates per 100,000: Chinese, 11.7 versus 12.5; Japanese, 11.5 versus 14.1; and Filipino, 8.1 versus 11.0) and was 10%-50% lower than the rate among U.S.-born white women (15.6 per 100,000). For Chinese and Japanese women, this overall pattern with birthplace largely reflected the experience of those aged 50 years and older; in younger women, the rates were somewhat higher among those born in the United States and were similar to those of white women. CONCLUSIONS These findings suggest that some descendants of Asian migrants to the United States retain a factor, genetic or otherwise, that partially protects against the development of ovarian cancer.