The activity of immobilized and native lipase and the stability of immobilized enzyme at various temperatures were determined. The highest activity of native enzyme occurred at 30 degrees C and the maximal initial activity of immobilized enzyme was observed at 45 degrees C. The best stability of immobilized enzyme was at 30 degrees C. The activity decreased with 0.8% per 24 h. The hydrolysis of sunflower oil by immobilized and native Rhizopus sp. lipase in the presence of surfactants, proteins and metals was studied. The native enzyme lost activity in the presence of cetylpyridinium bromide, Triton X-100, and sodium dodecyl sulphate (SDS) at concentrations of 0.1, 0.75, and 4 mM, respectively. The immobilized lipase was more resistant to inhibition than the native one. Bovine serum albumin, soybean trypsin inhibitor and ovalbumin had a small influence on the activity of the native lipase. However, BSA inhibited the immobilized enzyme. Cd2+, Zn2+, Hg2+ and Cu2+ inhibited the native enzyme while Cd2+ and Cu2+ strongly inhibited the immobilized one.