Semi-continuous batch process (SCBP) was developed for the production of paclitaxel from suspension culture of Taxus chinensis. Cell ages did not affect the specific production of paclitaxel, and it was possible to use the cells at day 21 as an inoculum for another cycle of production batch. Using SCBP, paclitaxel productions at day 42 were increased from 46.9 at cycle 1 to 85.5 mg l(-1) at cycle 4, but decreased at cycle 5 and 6. It was elucidated that the enhanced production of paclitaxel by SCBP was mainly due to the pre-treatment of silver nitrate.