Placental alkaline phosphatase phenotypes and activity were determined in 229 placentae obtained from Sudanese mothers. The estimated gene frequencies of the common alleles PlSl, Pli1 and Plfl were 0.7367, 0.1615 and 0.1018 respectively. There was a significant deviation from Hardy-Weinberg equilibrium with an excess of homozygous phenotypes, probably due to the high degree of inbreeding in the population. The enzymatic activity was 22.0 ± 12.5 to 26.4 ± 10.8 U/g placenta with no significant difference according to phenotypes
