Manganese peroxidase (MnP) production was performed in a airlift bioreactor in which Phanerochaete chrysosporium I-1512, an MnP hypersecretory strain, was immobilized on a stainless steel mesh. Production was scaled up from a 2.5-L bench scale to a 100-L bioreactor. The yield of MnP was increased 2-fold and reached 6600 U L-1. These results indicate the feasibility of MnP production on a medium scale, which promises sufficient MnP availability for its use in pulp bleaching at industrial scale.