Suspension cultures of Taxus canadensis were elicited with methyl jasmonate (MJ) under defined headspace ethylene concentrations. Kinetic studies of growth, nutrient consumption, pH variation, and paclitaxel accumulation were conducted in batch cultures and semicontinuous culture with total cell recycle. A dramatic increase of paclitaxel was obtained when the cultures were elicited with 100 mu M MJ, but cell growth was thereby arrested. Supplementation of acetyl-CoA and MJ to the culture proved to be another way to improve paclitaxel yields. Using semicontinuous culture with total cell recycle, paclitaxel accumulation was increased by a factor of 4.0 relative to that in the batch culture during 35 days of cultivation.