The effects of oleic acid on abnormal mitosis and apoptosis of Taxus cuspidata cells were investigated, when oleic acid improved taxol production in two-liquid-phase suspension cultures. The results showed that the addition of oleic acid (4%, v/v) led to an increase of cell apoptosis and a decrease of mitotic activity. Moreover, the occurrence of some abnormal cells, chromosomal doubling, chromosomal bridge, binuclei cells and micronuclei further confirmed that oleic acid disrupted the normal mitosis of T. cuspidata cells in two-liquid-phase suspension cultures. And the frequency of total abnormal mitosis was three to four times than that of apoptosis. It is, thus, inferred that oleic acid-induced abnormal mitosis and consequent apoptosis. We found that the increases in abnormal mitosis, the increases in cell apoptosis and the decreases in mitotic index are closely relevant to the enhancement of taxol production of T. cuspidata in two-liquid-phase cultures. (c) 2005 Elsevier Inc. All rights reserved.