Incidence was derived from published data from 2 population-based registries - the Philippine Cancer Society - Manila Cancer Registry and the Department of Health-Rizal Cancer Registry, which covered 8.5 million residents (1990 census) of a 1,674 square kilometer area that comprises Metro Manila and Rizal province. Thirteen registry clerks actively sought new cancer cases in 96 hospitals and 30 Civil Registry offices. Both registries are members of the International Association of Cancer Registries and received continuing professional assistance from the International Agency for Research on Cancer (IARC). For the period 1988-1992 the combined age-standardized incidence rate (ASR) was 9.9 per 100,000 for male stomach cancer (ranked fifth, 4.5% of all male cancers), and 5.9 per 100,000 among females (ranked ninth, 2.8% of all female cancers). Stomach cancer among Philippine residents had lower ASRs and age-specific rates compared to Japanese, Korean, Chinese, Singaporean Chinese and Vietnamese populations. Age-specific rates among Filipinos reached 10 per 100,000 or higher at age-group 50-54 years among males, and 55-59 years among females. Significant differences in incidence were observed in only few cities and municipalities. There were little differences in ASRs between 2 populations during 3 time periods between 1980-1992, in both males and females with an indication of a slight decrease. Incidence of male Philippine migrants to Hawaii, San Francisco and Los Angeles were comparable to those of white residents covered by the Manila registry. Among females, stomach cancer incidence of Philippine residents and Filipina migrants to Hawaii were similar, and were slightly higher than those of white residents in Hawaii and both migrants and white residents in San Francisco and Los Angeles