Clinicohematological investigations and cytogenetic analysis of blood lymphocytes were made 5-7 years after the Chernobyl accident in 201 liquidators who had worked in the radionuclide-contaminated zone. Among the somatic diseases found in the examinees statistically more prevalent were cardiovascular and gastrointestinal affections, asthenic syndrome, thyroid disorders. Hemograms presented a rise in hemoglobin, red cell and eosinophil content, a drop in the number of neutrophils. A tendency to erythrocytosis was observed in 20.3% of the wreckers. Dicenters and rings were abundant in the lymphocytes of 69% of the cytogenetically examined examinees 5-7 years after the exposure to radiation.