With the aim of determining the fatty acid (FA) selectivity of lipases, a mixture of oleic acid and monoacid triacylglycerols (TAGs) including tricaproin (T6), tricaprylin (T8), tricaprin (T10), trilaurin (T12), trimyristin (T14), tripalmitin (T16) and tristearin (T18) was used as the substrate in acidolysis performed in hexane. Three immobilized lipases, namely, Lipozyme TL IM from Thermomyces lanoginosus, Lipozyme RM IM from Rhizomucor miehei and Novozym 435 from Candida antarctica, were used as biocatalyst. The effects of operating variables including the mole ratio of oleic acid to monoacid TAG, temperature, enzyme dosage and reaction time on incorporation were also investigated. Significantly different incorporation rates were obtained for different TAGs used (P < 0.05). Incorporation of oleic acid into TAGs except tricaproin and tricaprylin was higher for all the TAGs with Lipozyme TL IM catalyzed reactions than those of other two enzymes tested. Incorporation of oleic acid decreased as the acyl chain length of FA in the TAG increased with Novozyme 435 catalyzed acidolysis. Compared to the other substrate mixtures, the highest incorporation was observed for oleic acid and tricaproin mixture with three lipases tested. It was shown that the FA selectivity of the lipases is strongly dependent on the acyl chain length of FA in a TAG.