Lipase-catalyzed acidolysis of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) oils with long-chain omega 3 polyunsaturated fatty acids (PUFA), namely, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, was carried out in hexane, and the products were analyzed using gas chromatography. The most effective lipase for incorporation of omega 3 PUFA into these oils was Pseudomonas sp. as compared to lipases from Mucor miehei and Candida antarctica. Response surface methodology was used to obtain a maximum yield of EPA+DHA incorporation while using the minimum amount of enzyme possible. The process variables studied were the amount of enzyme (159-350 units), reaction temperature (30-60 degrees C), and reaction time (6-30 h). All experiments were carried out according to a face-centered cube design. Under optimum conditions, incorporation of EPA+DHA was 35.5% in borage oil and 33.6% in evening primrose oil. The modified borage and evening primrose oils containing gamma-linolenic acid, EPA, and DHA were successfully produced and may have potential health benefits.