The enzymatic activities of wheat germ lipase (WGL) (EC.3.1.1.3; triacylglycerol hydrolase) in water-in-oil (w/o) microemulsions of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)/cyclohexane/water have been investigated by using triolein as the substrate through measurements of absorbency of the product of hydrolysis at the wavelength of 707 nm in the course of reactions. Maximum enzyme activity was obtained at ω0 (molar ratio of water to surfactant)=9, pH=7.4 and T=40℃. The activation energy of the reaction was calculated from the Arrhenius plot. It was found that the hydrolysis reaction obeyed Michaelis-Menten kinetics in the investigated concentration range (0.01-0.15 mol/l) of the substrate, and the apparent Michaelis constant Km,a and the apparent maximal reaction rate Vm were determined. The stability of wheat germ lipase in w/o microemulsions was also examined and discussed.