A total of 23 men complained of neurological symptoms after a single severe exposure to toluene di-isocyanate. Effects of exposure were immediate in five men and consisted of euphoria, ataxia, and loss of consciousness. These men and nine others complained of headache, difficulty in concentration, poor memory, and confusion during the next three weeks. Four years later it was found that nine further men had experienced symptoms that they had not been aware of at three weeks. In all, 13 men still complained of poor memory, personality change, irritability, or depression after four years. Psychometric testing showed a selective defect for relatively long-term recall in those with persistent symptoms at four years.