In order to determine the subcellular localization of alkaline phosphatase in human term placenta twenty-two cases of normal term placenta were preared by differen tial centrifugal method There were devided to whole homogenate uncleic fraction mitochondrial fraction microsomal fraction adn supernatant fraction And the specifc activity of alkaline phosphatase in each fractions was measured The results were as following: 1. The enzymatic activity of alkaline phosphatase in whole homogenate of term placenta was 429.23±105.71 K-A unit (King-Amstrong unit/mg of protein/30 minutes), and it was statistically signifcant(P<0.001) 2. The activity of alkaline phosphatase in nucleic fraction was 215,36±64.67 K-A unit (4.6%) 3. The activity of alkaline phosphatase in mitochondrial fraction was 2,056.10±699.49 K-A unit(44%) 4.The activity of alkaline phosphatase in microsomal fraction was 2,237.78±706.18 K-A unit(48%) 5. The activity of alkaline phosphatase in supernatant fraction was 151.46±32.27 K-A unit(3.3%) 6.The correlations of the specifc activity of alkaline phosphatase between whole homogenate and each fractions were statistically signkfcant(p<0.001)