An extracellular lipase from Pichia burtonii was purified to homogeneity by a combination of DEAE-Sephadex A-50 ion-exchange chromatography, Sephadex G-100 gel filtration, and isoelectric focusing. The purified enzyme preparation showed a single protein band corresponding to a molecular mass of 51 kDa on sodium dodecyl sulphate/polyacrylamide gel electrophoresis. The molecular mass of the enzyme was estimated to be 47 kDa on Superdex 200 gel filtration, suggesting that the enzyme was a monomeric protein. The pI was about 5.8, The optimum pH and temperature for the hydrolysis of olive oil were about 6.5 and 45 degrees C respectively. Rapid loss of the enzyme activity was observed above 30 degrees C in the absence of olive oil, but the addition of olive oil or trimethylolpropane diallyl ether greatly stabilized the enzyme, At 30 degrees C, the enzyme hydrolysed Spans and Tweens as well as simple triglycerides of short- and middle-chain fatty acids, Although the enzyme cleaved all the ester bonds of triolein, it showed some preference for the outer ester bonds.