Abstract: Objective To verify the conversion of oleic acid（OA）to 9,10-dihydroxystearic acid（DHSA）in human hepatic cancer HepG2 cells. Methods Twenty-four hours after HepG2 cells were inculated into a 24-well plate,the cells were cultured in a serum-free MEM medium containing 50μmol/L and 100μmol/L OA for 24 and 48h,respectively,for the measurement of DHSA and OA levels in cell lytic fluid and supernatant. Results The DHSA and OA levels were significantly higher in HepG2 cell lytic fluid and supernatant 24h after adding 50μmol/L and 100μmol/L of OA than in those not adding OA（DHSA:3.29±0.38ng/ml and 6.33±1.99ng/ml vs 2.08±0.61ng/ml;OA:645.07±142.81ng/ml and 1 341.6±349.69ng/ml vs 359.68±12.06ng/ml,P＜0.05）.Forty-eight hours after culture,the OA and DHSA levels were still higher in HepG2 cell lytic fluid containing 100μmol/L of OA than in its supernatant.No difference was found in DHSA between HepG2 cell lytic fluid with or without OA. Conclusion OA can convert to DHSA in human HepG2 cells.