The results of NIOSH machine safety research programs conducted since 1971 were summarized. The results of NIOSH analyses of data on severe occupational traumatic injuries were discussed. The data were taken from the NIOSH National Traumatic Occupational Fatality database, the Bureau of Labor Statistics Supplementary Data System, and occupationally related cases in the Consumer Products Safety Commission National Electronic Injury Surveillance System. The analyses showed that agricultural machines and lifting machines are the most frequent causes of machine related fatalities in the United States. Approximately 20000 occupational amputations occur annually. Of these, approximately 90% are related to machinery or equipment. Based on the analyses, NIOSH recommended that power presses, forklifts, stackers, lumber carriers, shears, slitters, slicers, saws, and tractors and towing vehicles be considered for future machine safety research. The results of a NIOSH sponsored roundtable for establishing priorities for future machine safety research were discussed. Topics discussed included human factors in robotized workplaces, the reliability of machine safety devices, and machine related injury data. Five classes of machines were proposed as priority areas for machine safety research: power presses, forklifts, shears and slicers, saws, and tractors.