These studies were carried out to investigate the residual behaviour of lebaycid and malathion organophosphorus insecticides on sugar-beet (vegetative parts and roots) plants. Determined residue half-life values (RL50) in vegetative parts were 14.4 and 14.7 hours for lebaycid and malathion , respectively.                 In vegetative parts, the initial amount detected of lebaycid (5.04 ppm) was less than the initial amount found of malathion  (40.90 ppm), while the initial concentration was undetected in sugar-beet roots for each of lebaycid and malathion. The vegetative parts did not have any detectable residues of lebaycid and malathion after 9 and 20 days from application, respectively. No detectable amount of lebaycid and malathion residues were found in the roots all days after treatment. So sugar-beet roots treated with each of the two tested insecticides could be used safely in sugar industry