Apoptotic cell death was observed in suspension cultures of Taxus chinensis var. mairei under normal cultivation conditions by using microscopy, total DNA agarose gel electrophoresis and in situ end-labeling of fragmented DNA. The morphological and biochemical changes of cells occurred mainly in the non-dividing cell clusters, indicating that the T. chinensis cells died mainly by apoptosis. There exists a close relationship between cell apoptosis and Taxol formation. Taxol concentration increased with the increase in content of apoptotic cells and reached a maximum (14.2 mg l(-1)) after 23 days of culture, corresponding to a maximum ratio of apoptotic to total cells of about 13%.