Penicillium citrinum produced a lipase activity (5786 U/l), on a vegetable oil refinery residue as carbon source, higher than the one (2630 U/l) obtained on olive oil. Lipase activity was measured with triolein as substrate and the free fatty acids released were estimated. Ammonium chloride (0.75%) was the best nitrogen source (6738 U/l) compared to ammonium sulfate (5670 U/l), and urea caused a decrease of 85% in this lipase production (898 U/l).