The effect of medium component on manganese peroxidase production by white rot fungus strain L-25 was investigated using a response surface method (RSM). The Mn2+ and Polypepton concentrations had a strong influence compared to the initial pH.The Mn2+ concentration affected the specific activity, while the addition of Polypepton elevated the extracellular protein concentration in the medium. Since the MnP activity depended on both the specific activity and extracellular protein concentration, the Mull? production could be expressed as a function of both the Mn2+ and Polypepton concentrations. Based on the response surface plot, the optimum medium components were predicted as 1.0 mM Mn2+, 45 g/L Polypepton and initial pH of 6.2. Large amounts of MnP (about 30 U/mL) were obtained using the optimized medium. This is the highest value reported up to now.