Elaszym® (10, 800Unit/day) was administered to 38 hyperlipidemic patients for 16 weeks. Those patients were classified to two groups according to their sensitivity to this drug in serum cholesterol level. In high responders, serum cholesterol was lowered from 273±13 to 231±11mg/dl (p<0.001) but in low responders, it was not changed significantly. About the background of these two groups, age, sex and type and level of hyperlipidemia were not different between them. Apoprotein E was decreased significantly in the both groups. Increase in apoprotein C-II and C-III were statistically significant in the low responders. Atherogenic index and ratio of total cholesterol—HDL cholesterol to apoprotein B were significantly decreased in the high responders. These changes of apoproteins might be related to anti-atherogenic action of this drug.