The polymorphism of seven enzyme systems in plum (Prunus domestica) was analyzed by vertical polyacrilamide gel electrophoresis in two different somatic tissues, bark and leaves. Variation among the studied plum cultivars was observed in Peroxidase. Interspecific hybrids between plum and apricot exhibited Aspartate aminotranspherase pattern with bands from both parents. This enzyme system my be used for plum x apricot interspecific hybrid identification.