The production characteristics for Taxol (paclitaxel) using free and immobilized cells of Taxus cuspidata were investigated in a perfusion culture bioreactor. Although the cell growth was inhibited by higher dilution rates, the specific production rate of Taxol was increased by perfusion compared with that using batch operation. Perfusion cultures using a nylon-mesh cell separator for free suspension cells showed similar production profiles to those obtained using immobilized cells. Continuous Taxol production was successfully obtained at an approximate specific production rate of 0.3 mg/g DCW (dry cell weight) per day for up to 40 days.