Maiathion degradation was studied 01 vitro and in vivo during the period from 2002-2004 to investigate the biological removol of organophosphorus insecticide. malathion. by A. niger. A. flavus and T. virfde as a sole phosphorus source and to determine its residues and its major metabolities. Results indicated that malathion was not toxic to tested fungi at concentration up to 500 ppm. in vitro tests showed that fungal growth and fresh weight was increased by increasing the concentration of insecticide applied to some extent A. niger degraded malathion more efficiently than did A. flevus and T. Wide. As a result of inoculation with biodegraders. 96 loss in complete Dox medium was 90.5. 92.2 and 95% compared to 91.3. 93 and 98% in P—free medium when inoculated with T. wade, A. flevus and A. niger. respectively.“0.S. S—trimethyl phosphorodithioate was the major metabolite. inoculation of malathion- treated sawdust. as a growing medium. with A. niger improved significantly millet growth and this effect was more pronounced when incubation period with the fungus was increased. These results suggest the use of these candidates for bio- d'isposai of malathion.