OBJECTIVE: To explore the effect of microRNA (miRNA)-34c on the proliferation of ovarian epithelial cancer cells (OV-1063) by regulating the expression of E2F3. STUDY DESIGN: RT-PCR was used to detect the expression level of miRNA-34c mRNA in ovarian epithelial tissues and ovarian epithelial cancer tissues. OV-1063 cells were transfected by miRNA-34 MIMIC (miRNA-34c analog), and transfection was detected by RT-PCR. After OV-1063 cell experiment group and OV-1063 cell control group miRNA-34c 24 hour, 48 hour, and 72 hour relative expression of mRNA to test whether OV-1063 cell transfection was successful. After successful transfection, MMT method was used to de- tect OV-1063 cell proliferation ability. Transwell assay was used to detect OV-1063 cell invasion ability. Western blot method was used to detect OV-1063 cell E2F3 protein expression level. RESULTS: Compared with ovarian epithelial tissues, the expression of miRNA-34 in ovarian epithelial can- cer tissues was significantly downregulated (p<0.01); compared with the control group, there was no differ- ence in the proliferation ability of OV-1063 cells 24 hours after transfection (p>0.05). After 48 hours and 72 hours, the proliferation ability of OV-1063 cells was significantly weaker than that of the control group (p<0.01). The invasion ability of OV-1063 cells after transfection was significantly lower than that of the control group (p<0.01). E2F3 in OV-1063 cells after transfection MRNA and protein expression levels were significantly lower than the control group (p<0.01). CONCLUSION: miRNA-34c can reduce the prolifera- tion and invasion of ovarian epithelial cancer cells by downregulating the expression of E2F3, thereby exert- ing an anti-tumor effect. MiRNA-34c and E2F3 may be potential therapeutic targets for ovarian epithelial cancer. (Anal Quant Cytopathol Histpathol 2021;43: 806-812) © Science Printers and Publishers, Inc. © 2021 Science Printers and Publishers Inc.. All rights reserved.