Seven fungi have been experimentally screened to get the most active two lipase producers. The experimental conditions were Czapek's yeast extract tributyrin emulsion (CYET) liquid medium, incubated at 30 °C &pH 5.0 for 8 days. Classical kinetic technique of enzymatic analysis has been used to study the effect of physical factors (pH, temperature &incubation period). Optimal yield of lipase produced by Aspergillus niger after 8 days of incubation at 30 °C &pH 5.0, while optimal yield of lipase produced by Rhizopus nigricans after 6 days of incubation at 30 °C &pH 6.0. Conclusively, from this study, it could be concluded that the optimal yield of lipase was produced by Aspergillus niger at pH 5 and 30 °C for 8 days incubation, while the optimal yield of lipase produced by Rhizopus nigricans at pH 6 and 30 °C for 6 days incubation.