Since the traditional approach to optimization of biological systems based on the single variable search technique is incapable of detecting the true optimum when a number of chemicals are used together as inducers, the Evolutionary Operation (EVOP)-factorial design technique was applied successfully to optimize the concentrations of vitamin (biotin), metal ion (CaCl2) and plant hormone (NAA) for maximizing enzyme (protease) production by Rhizopus oryzae (RO IIT RB-13, NRRL-21498) in solid state fermentation,Addition of inducers to an optimal level (biotin-2.5 ppm, CaCl2-20 ppm and NAA-12.5 ppm) resulted in a similar to 1.9-fold increase in protease production.