Résumé : The results presented in this paper describe for the first time the presence of an inducible enzyme in the biosynthetic pathway leading to the anticancer drug paclitaxel. Methyl jasmonate, when administered to Taxus baccata cell suspension cultures, was found to rapidly induce geranylgeranyl diphosphate (GGPP) synthase activity. Experiments showed that after elicitation at day 7 of the subculturing period, the enzyme activity is rapidly induced during the first 6 h and reaches its maximum of 60.7 μkat/kg of protein after 5 days. The enzyme's induction was followed by a sharp increase in taxane accumulation in the cells, which started 24 h after elicitation and reached its maximum after 5 days. In addition taxine-B was found in the medium of unelicited cultures but not in the medium of elicited cells.