Objective To observe the effects of retinoic acid （RA） on the proliferation and differentiation of a human ovarian carcino-ma cell line: 3AO cells. Methods 3AO cell proliferation was evaluated by viable cell count

percentage of cells in each cycle phase were analyzed by flow cytometric analysis

alkaline phosphatase （AKP） activity was determined as described

and CA125 expression was measured by ELISA. Results RA could inhibit the proliferation of 3AO cells accompanied with morphological changes in a dose-dependent manner. Cell cycle analysis indicated that RA inhibition of 3AO cells growth occurred through induction of G1 arrest with a concomitant reduction in the proportion of cells in S phase

AKP activity increased significantly after treatment with RA（0.1 μmol/L） for 1-5 days. Dose-response studies revealed that the AKP activity increased to a different extent as a function of RA concentrations. Furthermore

RA could suppress the expression of CA125 tumor marker in 3AO cells.Conclusion RA could markedly inhibit the proliferation and induce the differentiation of 3AO cells. for 1-5 days. Dose