Twenty repeated 7-hour exposures of male rats to 10,000 ppm of vinyl bromide resulted in an observable decrease in activity during the exposures and a significant decrease in gain of body weight. No noteworthy gross or microscopic pathological changes were detected in the major organs and tissues. Repeated 6-hour daily exposures of groups of male and female rats, rabbits, and monkeys, to either 2,50 ppm or 500 ppm of vinyl bromide vapor, for a period of 6 months were also investigated. There were no compound-related effects with respect to demeanor, body and organ weights, food consumption, a number of hematological parameters, or mortality. Gross and microscopic examination of the major organs and tissues revealed no remarkable abnormal changes. Slight increases in blood bromide concentration were detected in the experimental animals. An inference from the experimental data for an industrial situation suggests that repeated exposure of workmen to vinyl bromide should not exceed 500 ppm, and that the time-weighted average should not exceed 250 ppm. It may also be desirable to monitor the blood bromide level, although other sources of bromide such as medication and drinking water may be contributing factors. Precautions for safe industrial handling are discussed.