An elevation of chromosomal aberrations has been found in the lymphocytes of alcoholics compared with those of nonalcoholics. In this study, structural aberrations of chromosomes in peripheral lymphocytes of alcoholics and former alcoholics were examined in order to study the chromosome-breaking activity of alcohol and effects of long-term sobriety on chromosomal aberrations in alcoholics. We have presumed initially that chromosomal aberrations in alcoholics would remain for a long time after abstinence from alcohol. Nevertheless we found a spontaneous reduction of the chromosomal aberrations in former alcoholics who had been dry for periods of 2 years or more. These observations suggest that chromosomal aberrations appearing in alcoholics probably formed by a chronic activity of alcohol and/or its metabolic products and cellular repair mechanisms may recover within a few years of abstinence.