In a sample of the Polish population of 261 unrelated adults, six types of phosphoglycolate phosphatase (PGP) were encountered. From the distribution of phenotypes obtained, the following frequency of genes was calculated: PGP1 = 0.8429, PGP2 = 0.1399 and PGP3 = 0.0172. PGP types were also determined in 12 families with 30 children and in 55 mother-child pairs. In the group of children the observed distribution of types was consistent with assumed types. The usefulness of this system in disputed paternity cases is as high as 13.52%.