Serum levels of organochlorine pesticides (OCP) were measured in agricultural workers from Rio de Janeiro State, Brazil. Blood samples from 26 volunteers (24 males, 02 females, 17-60 years old) were taken in October 1997. OCP residues (op'DDT pp'DDT, pp'DDD, pp'DDE, aldrin, dieldrin, endrin, heptachlor, heptachlor-epoxide, alpha-, beta- and gamma-hexachlorocyclohexane, and hexachlorobenzene) were analyzed by gas chromatography with an electron capture detector. Tests detected pp'DDE in 16 out of 26 samples, but pp'DDE concentration exceeded 1.4 µg/L (i.e. 1.8, 2.4 and 4.4 µg/L) in only 3 of these. beta-HCH was found in 6 (23.1%) out of 26 samples. In one sample beta-HCH did not exceed 1.4 µg/L, but in the remaining samples concentrations ranged from 1.4 to 5.3 µg/L. The percentage of positive pp'DDE samples increased from the youngest (£29 yrs: 30.0%) to the oldest age group (³ 40 yrs: 100%). A similar trend was found for beta-HCH contamination (£ 29 yrs: 0%; 30-39 yrs: 20.0%; ³40 yrs: 66.7%). Dieldrin (3.7 µg/L) was found in only one sample. No other OCP residue was found in the samples. Serum concentrations of OCPs found in this study are comparable to levels reported for the non-occupationally exposed population in Brazil and elsewhere.