The influence of cultivation conditions on the pellet size and manganese-dependent peroxidase production by Phanerochaete chrysosporium was investigated. The influence of the agitation rate, inoculation level, and medium composition was assessed systematically. The strong variation in enzyme production with the agitation rate and inoculation level is caused by the pellet size differences. When the enzyme activity was varied by changing the amount of carbon and nitrogen sources in the medium, no such correlation with the pellet size was observed.