Objective: The aim of this study was to construct THY1 eukaryotic expression plasmid and study its effects on ovarian cancer SKOV3 cells. Methods: The gene fragment coding for THY1 was obtained from human normal ovarian tissue using RT-PCR, and inserted into the eukaryotic expression plasmid pcDNAJ.1 (+) to construct the recombinant plas-mid pcDNA3.1(+)-THY1, which was transfected into SKOV3 ceils. The experimental cells were classified into three groups:SKOVJ-THY1, SKOVJ-Null and SKOVJ. The expression of gene was measured using RT-PCR and Western blotting. The percentage of apoptotic cells and cell cycle analysis and cell proliferation were assessed by flow cytometry and MTT assay.Both SKOVJ-THY1 and SKOVJ-null cells were inoculated subcutaneously into nude mice to determine in vivo tumorigenicity.Results: The gene fragment of THY1 was correctly inserted into the eukaryotic expression plasmid pcDNAJ.1 (+) and veri-fied by PCR, restriction endonucleases digestion and DNA sequencing and the plasmid of pcDNAJ. I(+)-THY1 (THY1 geneoverexpression) has been stably transfected into SKOV3 cells. The analysis of flow cytometry indicated that the pcDNAJ. 1(+)-THY1 transfected cells in G1 phase were significantly elevated, but in S phase were decreased. The growth of transfected cells was suppressed, and more apoptosis cells were identified in pcDNAJ.I(+)-THY1 transfectants compared with vector vehicle transfectants. The tumor suppressing activity of THY1 in SKOV3 cells was associated with inhibition of SKOV3 cellular proliferation, in vivo tumorigenesis in nude mice. Conclusion: THY1 transfection can inhibit the growth of SKOV-3 cells in vitro and in vivo. THY1 gene 5 play an important role in generation and development of ovarian cancers.