The isoperoxidase spectrums of 2 single tulip cultivars and their parrot mutants were analyzed by disc electrophoresis in leaves and tepals i.e. petals plus sepals excised from within the bulbs. It was found that the anodal isoperoxidase pattern of parrot mutant tepals differs distinctly from tepals of their mother cultivars, but no differences were observed in cathodal isoperoxidases. Both the anodal and cathodal isoperoxidase spectra of parrot mutant leaves and leaves of their mother cultivars were similar.