1. The document examines the effect of various phytohormones on the activity of endopolygalacturonase (EPG) enzyme produced by Alternaria cepulae. It finds that 100 ppm concentrations of gibberellic acid, naphthalene acetic acid, and indole butyric acid significantly inhibited the activity of purified EPG enzyme. 2. The phytohormones were also found to inhibit the activity of other extracellular enzymes produced by A. cepulae like cellulase, xylanase, and proteinase, though their inhibitory effect was less than on EPG. 3. The results suggest that phytohormones may play a role in plant