Three follow-up surveys from 1976 to 1985 were carried out on 193 subjects who developed chloracne following the Seveso accident (1976). A comparison group, age and sex matched, was selected randomly from the municipal list of Varedo (in the same health district but out of dioxin polluted zone). At each follow-up a questionnaire was administered and biochemical tests, skin examination and electrophysiologic measurements were performed. Biochemical indicators of hepatic function and nerve conduction studies did not show either significant differences between groups or temporal trends. Chloracne was shown to be clinically reversible: all the chloracne cases (except for one subject) clinically recovered by 1983. The discrepancy between our results and the previous experiences can be related to: different type of exposure, target population and interval since exposure.