The use of existing data sources for occupational disease surveillance was discussed. Data collected by federal and state health and administrative data systems may be useful for occupational disease surveillance. To be useful, information on conditions related to occupational exposure must be included in the data system and the conditions must occur regularly in the geographic area under surveillance. Information on the occupations of workers in the data system must also be included or accessible. A proposed national occupational mortality data system based on state death certificates was described. The system was initiated in 1981 by 40 states and the District of Columbia with the support of NIOSH, the National Center for Health Statistics (NCHS), the National Cancer Institute, and the Bureau of the Census. Starting in 1988, 23 states are expected to send industry and occupation data on deceased workers to the NCHS in machine readable form. Other data systems useful for occupational disease surveillance were described. These included cancer registries, state workers' compensation boards, hospital discharge records, and miscellaneous sources such as the NCHS National Health Interview Survey and the Social Security Administration. The authors conclude that extant data sources can make a significant contribution to recognizing and ultimately controlling occupational diseases in the United States. Diseases with long latency periods can be assessed from death certificates or registries. Those with relatively short latency periods can be identified from physicians' reports.