Eight milk proteins (whey protein concentrate, a-lactalbumin, beta-lactoglobulin, isoelectric casein, micelar casein, Na caseinate, alpha(s1)-casein and beta-casein) were degraded with serine protease isolated from Asian pumpkin (Cucurbita ficifolia) by hydrolysis at 37 degrees C, pH 8.0 and the enzyme dose 150 U/mg of the protein. The proteolysis was monitored by detn. of hydrolysis degree and free NH2 groups release and by electrophoresis and reversed-phase high-performance liq. chromatog. The highest hydrolysis degree 41.6% was achieved after 24 h long treatment. The susceptibility of the milk proteins to serine protease was confirmed.