A record of all known cases of nasopharyngeal carcinoma in Malaysia is complete for 10 years from 1968 to 1977. Special efforts in case-finding were made in the State of Selangor where conditions are optimal. Age-adjusted incidence rates among Chinese males and females were 16.5 and 7.2 per 100,000, among Malay males and females 2.3 and 0.7 and among Indian males, 1.0. There were no significant changes in incidence rates over the 10-year period for sex and ethnic groups, or for Chinese subethnic groups. In Chinese subethnic groups, rates were highest among Cantonese, moderate among Khek and lowest among Hokkien and Teochiu. Standardized incidence ratios using Selangor as the standard population indicate considerable under-reporting in the less urban states of Malaysia, particularly among females. In Selangor, incidence rates were similar for urban and rural residents, but the frequency of cases was higher among Chinese working in industry and living in poor neighbourhoods.