In an attempt to produce the polyunsaturated fatty acid (PUFA)enriched glycerides, commercially available Turkish anchovy oil (PUFA content of 27%), was hydrolyzed with 1,3-specific Rhizomucor miehei lipase. After the hydrolysis, the triglyceride (TG), diglyceride (DG), monoglyceride (MG), and free fatty acid (FFA) composition of the reaction mixture was determined, and fatty acid components of these fractions were analyzed. R. miehei lipase released PUFA extremely slowly, resulting in their accumulation in the TG and DG fractions, especially in TG. The PUFA content in the glyceride mixture (including TG, DG, and MG) increased as hydrolysis progressed. The effects of operational parameters (pH, temperature, time, and enzyme concentration) on the extent of hydrolysis were investigated. Based on these results, optimal reaction conditions were established. At optimal conditions (pH 4.0, 35 degrees C, 3 h, and enzyme concentration of 500 U/g oil), the level of PUFA in the glyceride mixture was raised to 40%. The individual TG and DG fractions contained 45 and 30% PUFA, respectively. Less than 2% of the total PUFA was lost in the FFA fraction.