Low concentration of phenothiazines apparently stimulated the proliferation of S. pombe, the cell density incubated for 54 hours by preincubating the cells with 20 mumol/L trifluoperazine (TFP) in the EMM-Ca medium was two times more than the control. The stimulation was more obvious with lowing the concentration of calcium in the culture medium, TFP cooperated and complemented with calcium in stimulating the proliferation of S. pombe. When the original inoculated cell density was 5 x 10(6) cells/ml or during the logarithm period of growth curve, the proliferation of S. pombe wasn't affected by the low concentration of TFP. While when the concentration of TFP was increased to 100 mumol/L, the promotion effect of TFP on proliferation of S. pombe declined obviously and the proliferation of S. pombe was inhibited completely when TFP up to 200 mumol/L. The cell proliferation also could be inhibited by CaM antagonist W7 and W7-agarose, the inhibition was increased with increasing the concentration of antagonist. On the other hand, 20 mumol/L TFP used by the same method as above arrested the cell division cycle of Saccharomyces cerevisiae at a single G2 + M nuclei stage, the cells was penetrated easily by TFP, the fluorescence in cells was very obvious when TFP was 20 mumol/L, but it was difficult to penetrat by TFP in the cells of S. pombe and the Ca2+ influx of S. pombe could be induced rapidly by 20 mumol/L TFP. In this article, the cause of different effects of TFP on cell proliferation of S. pombe and S. cerevisiae was discussed, it was due to the difference of penetration of TFP and stimulation by calcium in the two kinds of cells.