With polyacrylamide gel electrophoresis, peroxidase isoenzyme patterns in the terminal buds of grafted, 20-year-old Pinus elliottii trees were compared between abundant-flowering and poor-flowering trees during the period of female flower bud initiation. A total of nine peroxidase bands were observed in the terminal buds. The total amount of peroxidase enzymes in slash pine buds showed no significant difference between the abundant-flowering and poor-flowering trees. However, the fifth band from the gel front was observed in all the samples of abundant-flowering trees throughout the sampling period (July 8 to September 17), while this band was absent in most of the poor-flowering trees.