This study reports the use of different inducing agents (olive, soybean, and used frying oils) and culture mediums [synthetic medium (SM), whey protein, and corn steep liqueur (SL)] to optimize the production of lipase by Fusarium oxysporum. A relationship among the inoculum size, presence of a fat source, fungal growth, and lipase production was evident during the fermentation. The best results were achieved when the inoculum was grown in SM or SL and the fermentation was developed in SM with frying oil as the inducing agent. The maximum activity (about 15 U/mL) was obtained after a 72 hr cultivation.