Abstract: Objective 　The study was to research Fas expression and int racellular calcium content change in human cervical carcinoma Hela cells t reated with arsenic t rioxide. Methods 　MTT method was used to observe the growth inhibition. Apoptosis was detected with Annexin V-FITC + PI dual parameter. Fas positive rate and int racellular calcium ions ( IECa ²⁺ ) levels were measured by flow cytometry in Hela cells treated with As₂O₃ . Results 　As₂O₃ could inhibit the growth of Hela cells dramatically. There was obvious dosage-effect and time-effect correlations, it s half inhibitory concent ration ( IC50 ) at 24h, 48h and 72h were 8. 62μmol/ L, 6. 77μmol/ L and 4. 89μmol/ L respectively. Apoptosis rate increased in Hela cells t reated with As₂O₃ . As₂O₃ could increase Fas expression and IECa ²⁺ levels in Hela cells ( P < 0. 01) . Conclusion 　As₂O₃ could inhibit the growth of Hela cells dramatically and induce apoptosis, we proposed that its mechanisms were probably associated with the improved Fas expression and IECa ²⁺ levels.