Neurologic and psychiatric symptoms such as headache, tinnitus, defective hearing, changing desorientation and aggressiveness are initial symptoms of methyltin chloride intoxication. Some patients also developed epileptic equivalents, such as dreamy attacks and central ventilation transaminases. Laboratory findings included low levels of serum potassium, leucocytosis and elevated transaminases. The excretion rate of tin in the urine correlated with the severity of the intoxication. There was no measurable effect of plasma separation or d-penicillamine therapy on tin excretion in the urine or on the clinical picture. The long-term prognosis of severely intoxicated persons is poor. Neurohistopathologic findings confirm the animal studies by Brown et al and the severe damage and cell necrosis in the hippocampus area. To prevent such events workers need to be warned of the risk and dangers of working with organo-metallic compounds. The effectiveness of protective clothes and gas masks should be checked. In exposed workers regular testing is advised of tin concentrations in the urine.