The NIOSH worker notification program was described. The program was started by the Industrywide Studies Branch of NIOSH in 1988 and designed to communicate the findings of epidemiological studies to workers who were subjects in the studies. The notifications were of two types: a poster that summarized the findings of the study at the worksite or an informative letter that was sent to each surviving study group member. Both methods included the name and toll free number of a NIOSH contact person for additional information. Since 1991, reader response cards have been provided in some individual notifications to encourage worker feedback. The workers were asked to rate the notification materials on a five point scale. The results of analyses of work responses to seven notifications were discussed. The notifications were all individual letter notifications of retrospective cohort mortality or cancer incidence studies of workers exposed to carbon-monoxide (630080) (CO), o-toluidine (95534), bis-chloromethyl-ether (542881) (BCME), polychlorinated biphenyls (PCBs), cadmium (7440439), acid mist, and 2,3,7,8-tetrachlorodibenzo-p-dioxin (1746016) (TCDD). The studies found increased risks for arteriosclerotic heart disease, bladder or lung cancer, melanoma, kidney dysfunction, laryngeal cancer, all cancers combined, or soft tissue sarcoma. The workers responded to the notifications of the CO, o-toluidine, BCME, and PCB studies by telephone, and the cadmium, acid mist, and TCDD studies by postcard. Telephone calls ranged from 0.3% for the CO notification to 3.8% for the BCME notification. The percentage of postcard responses ranged from 0.3% for the cadmium study to 2.1% for the TCDD notification. The two largest groups of respondents had questions about their disease risk or reported on their health status, 30 and 25%, respectively. The two largest categories of open ended comments were favorable comments about receiving the notification letters or reports of ill health, 26 and 20% of the respondents, respectively. About 66% of the respondents rated the notification materials favorably and 85% found them easy to read.