A method is described for the simultaneous extraction and determination of twenty organochlorine pesticides residues hexachlorocyclohexane (HCH) isomers (α, β, γ, δ), aldrin, dieldrin, endrin, heptachlor and its epoxide (HE), hexachlorobenzene (HCB), α‐endosulfan, o,p′‐DDD, p,p′‐DDD, o,p′‐DDE, p,p′‐DDE, o,p′‐DDT, p,p′‐DDT, dicofol, methoxychlor, and mirex that were spiked in tomatoes. Samples were extracted with ethyl acetate, and the extract was subjected to a rapid clean‐up using a Florisil column. The residues were determined by GLC‐ECD using two columns of different polarity. The calibration graph correlation coefficient ranged from 0.9903 to 0.9990. The recoveries ranged from 95 to 99% with relative standard deviation ranging from 0.5 to 14.7% in the concentration range 0.005 to 0.2 μg/g. The limits of detection ranged from 0.004 to 0.05 μg/g and the limits of quantification ranged from 0.005 to 0.174 μg/g.