Abstract: Beef tallow stearin and beef tallow olein were interesterified with soybean oil using sodium methoxide or immobilized lipases from Rhisomucor miehei (Lipozyme IM) and Candida antarctica (Novozym 435) as catalysts. It was found that after interesterification the contents of free fatty acids and of mono- and diacyloglycerols increased. The slip melting point and solid fat content of the triacylglycerol fraction isolated from interesterified samples containing stearin were lower compared with nonesterified blends. For interesterified mixtures containing olein and soybean oil opposite dependencies for slip melting point and solid fat content were observed. The total fatty acids composition of fats before and after interesterifications remained unchanged but their distributions between sn-1, 3 and sn-2 positions were modified depend on catalysts used. These distributions were random after chemical interesterification or close to random when Novozym 435 was used. When Lipozyme IM was used the fatty acid composition at sn-2 position remained practically unchanged compared with starting blend.