Results from the identification of a collection of 43 table grape (Vitis vinifera L.) cultivars by isoenzymes from woody stems are presented. Plant extracts were separated by polyacrylamide gel electrophoresis. Isoenzyme analysis was carried out for peroxidases, catechol oxidase, glutamate oxalacetate transaminase, superoxide dismutase, esterases, and acid phosphatase. The last two systems were not adequate, while the rest showed a more or less marked polymorphism. Catechol oxidase was the system with the highest level of polymorphism. The combination of the zymograms allowed the separation of 31 out of the 43 studied cultivars. The other 12 cultivars were separated in five groups. The use of this methodology for differentiation of grapevine cultivars is recommended.