Acute organophosphate poisoning is known to result in substantial behavioral abnormalities. We assessed psychiatric manifestations of exposure in workers less substantially exposed to organophosphate compounds and showing no obvious signs of toxicity. Commercial pesticide sprayers and farmers recently exposed to organophosphate agents were compared to control subjects on personality tests, a structured interview, and cholinesterase level. The commercial sprayers but not the exposed farmers showed elevated of anxiety and lower plasma cholinesterase than control subjects. Assessment of other behavioral manifestations and red blood cell cholinesterase failed to disclose other group differences. These findings are viewed as tentative until confirmed by additional study, but they point to the possibility that organophosphate compounds may produce subtle defects in workers who are not obviously toxic. The findings do not justify public alarm but do suggest an area warranting more systematic and definitive investigation.