The effect of gibberellic acid (GA₃) and abscisic acid (ABA) on KCl -enhanced proteolysis of senescing leaves of rice (Oryza sativa L. cv. Chilsung) was studied. Emphasis was given to their effects on KCl-enhanced efflux of amino acids and proteinase activity. When treated singly, GA₃ affected leaf proteolysis little, while ABA increased proteolysis, the rate of amino acid efflux, and ribulose - 1,5-bisphosphate carboxylase /oxygenase (Rubisco)-degrading endoproteinase activity. An additive increase in all three parameters mentioned above was observed when leaves were treated with ABA and KCl. No such an additive effect was found when GA₃ was treated with KCl. Both GA₃ and ABA helped to alleviate the KCl - suppressed activity of Rubisco-degrading exoproteinases. The additive increase in proteolysis of rice leaves in the presence of both ABA and KCl could thus be ascribed to a further increase in the efflux of protein hydrolyzates and Rubisco-degrading endoproteinase activity. An increase in proteolysis was accompanied by a decrease in water absorption, and the combined treatment of ABA with KCl resulted in a further reduction of water absorption.