The addition of cell extracts and cultures filtrate of Pencillium minioluteum, Botrytis cinerea, Verticillium dahliae, and Gilocladium deliqucescens on the tenth day after transferring Taxus sp. (R01-M28) cell suspensions into an induction medium, further improved the production of Taxol(R) and total taxanes. Arachidonic acid (1mg/L) addition at the time of inoculation increased Taxol production by 150%. Oxidative stress induction and copper sulphate or sodium orthovanadate addition had no effect on Taxol production. Three categories of elicitors; those specifically stimulating Taxol production, those specifically stimulating the producion of other taxanes, and those stimulating taxane production uniformly, could be identified. The biosynthetic site of action of these elicitors is currently not known.