Screening of twenty four bacterial organisms for their lipase ac­tivity revealed that they have different enzymatic potentialities. Bacillus subtilis (12) was the most active strain. Fifteen fungal strains and seven yeasts were also tested for lipase activity. Aspergillus oryzae and Sac­charomyces cervisiae (4) were found in the greatest order for fungal and yeast strains. A 9.0%, 0.1% and 0.2 M of acacia gum, sodium de­soxychlorate and Ca+², respectively seemed to be optimal activators for lipase activity. The highest levels of Pseudomonas aeruginosa, Cellulo­mynas sp. (9), Saccharomyces cerevisiae (4) and Aspergillus oryzae were achieved at pH 7.5, while pH 8.5 exhibited similar effects on Bacil­lus subtilis (12) and Aspergillus flavus (2) as regards to lipase activity. The highest enzyme activity was recorded at 40°C for Pseudomonas ae­rugionsa, Cellulomonas sp. (9), Saccharomyces cerevisiae (4) and Aspergillus oryzae. Whilst, 35°C showed similar activity for Bacillus subti­lis (12) and Aspergillus flavus (2). Olive oil was the favourable substrate among oils studied for lipase activity in all microorganisms.