The authors gave 22 chemical workers neurological, psychiatric, and neuropsychological examinations and placed them in one of two groups according to their degree of exposure to trimethyltin chloride spillage during January 1978. Other chemicals to which they had been exposed were dimethyltin dichloride and methyl chloride. Specific and nonspecific symptoms of intoxication of the CNS showed a significantly greater frequency in the highly exposed group, including cycles of depression and destructive rage, each lasting a few hours. These observations should alert diagnosticians to this type of occupational exposure.