Abstract: A method was described for determining erythrocyte acid phosphatase (EAP) phenotypes from fresh human blood and bloodstain by thin-layer polyacrylamide gel isoelectric focusing (PAGIF),obtaining arrow,even, clear isoenzyme bands Some of the advantages of thin-layer PAGIF were increased resulation and dried bloodstain for twomonthes can be detected. Using this method,We detected the EAP phenotypes from 283 unrelated individuals in Shanghai.The results were as follows:EAP A 4.24%,EAP BA 28.98%,EAP B 66.78%;p~a=0.187,p~b=0.813;Did not find p~c.The discriminating power (DP)of EAP was 0.47.