Soil samples were polluted with fluoranthene and treated with CaO2 to study the decompn. of the hydrocarbon pollutant The soil toxicity was studied during bioremediation process with use of earthworms Eisenia fetida. Neither acute toxicity test nor avoidance test showed any effect of the treated soil on the earthworms. The addn. of CaO2 (12 mg/100 g dry mass of soil) was sufficient to initiate and accelerate the decompn. of fluoranthene.