Genetic variation was studied in a Zairean oil palm germplasm collection by employing native polyacrylamide gel electrophoresis of isoenzymes. Three isoenzymes extracted from leaves, namely superoxide dismutase (SOD), peroxidase (PRX) and glutamate dehydrogenase (GDH) were investigated. Polymorphism was detected in SOD and PRX systems but there was no genetic variation in GDH system. Polymorphic indices obtained from SOD and PRX systems revealed that the degree of polymorphism increased from the family to the ecotype level. This study also showed that the degree of polymorphism is influenced climatically and geographically.