The effect of Olesil on decay dynamics of zineb, mankozeb, and ethylenethiourea residues in black-currant and apple treated during the vegetative stage with fungicides; Cynkotox and Dithane M - 45 together with Olesil, was investigated. Zineb and mankozeb were assayed colorimetrically using methylene blue, and ethylenethiourea was determined by gas chromatography after formation of chlorobenzyl and trifluoroacetic derivative. No effect of Olesil on decay rate of Cynkotox and Dithane M - 45 residues in black-currant and apple, was found.