Edible mushroom Pleurotus sajor-caju was grown under submerged condition in deproteinized whey supplemented with diammonium hydrogen phosphate and plant growth hormones, viz. indole-3-acetic acid (lAA), gibberellic acid (GA(3)) and kinetin (KIN). The hormones, at different concentrations. increased the biomass production of P. sajor-caju by 15-26%. However, increase in protein content of the mycelia was relatively small (3-5%) over the control. Maximum enhancement was observed with indole-3-acetic acid. Twenty-eight percent more protein could be harvested from 11 of whey containing 2 mg 1(-1) of indole-3-acetic acid. (C) 2004 Elsevier Ltd All rights reserved.