Cytogenetic analysis of peripheral blood lymphocytes was used to compare 58 shoe workers (57 men and one woman) exposed to benzene and 20 subjects selected from the general population not exposed to particular mutagenic or carcinogenic agents (control group). Frequencies of damaged cells, including gaps, breaks, and rearrangements (acentric fragment, deletion, translocation) were scored for both groups. The incidence of chromosomal aberrations (particularly chromatid gaps and breaks) in the exposed group was significantly higher than in the control group. There were no effects of smoking and only breaks were affected by alcohol. Nor was there a significant relation between the working period in the group exposed to benzene and frequency of chromosomal aberrations.