The data available on the distribution of variants, phenotype and gene frequencies of different placental isoenzymes, especially for caste populations of Andhra Pradesh, are very scanty. In the present study, phenotype and gene frequency distributions of placental alkaline phosphatase (PLAP) of two caste groups namely, Lambada and Perika of Andhra Pradesh, South India, are reported. All the common phenotypes and the single case of a rare phenotype have been observed in the Lambada group.