A follow-up study has been conducted of 60 workers occupationally exposed to benzene for a period of 2 months to 19 years. Duration of the study was 18 years. All subjects were traceable. Ten deaths were recorded, four due to malignancies. No leukemia was observed. Increase of hemoglobin, platelets, white cells, neutrophils, lymphocytes and decrease of monocytes were observed between 1960-1964 and 1980, a fact which suggest a slight initial hematologic disorder in relation to benzene exposure which returned to normal thereafter.