Abstract: Objective To observe the therapeutic effects of arsenic trioxide combined with transcatheter arterial chemoembolization in treatment of primary liver cancer and pulmonary metastases. Methods Total of 64 patients were randomly divided into treatment group (n = 30) and control group (n = 34).  treatment group received periodic transcatheter arterial chemoembolization (TACE) and 10 mg arsenic trioxide by intravenous infusion for 5 hours per day, 3 days after TACE. Each cycle of treatment persisted for 14 days with a interval of 2 weeks and 3-4 cycles were administered continuously. Patients in control group received periodic TACE merely. Objective efficiency, benefit rate, quality of life and the correlationship with metastatic tumor size and number in both groups were recorded. Results The objective efficiency was 26.7% (8/30), and the benefit rate was 60.0 (18/30) in treatment group, while 0 (0/34) and 17.6% (6/34) in control group respectively, with significant statistical differences (χ 2  = 7.067, P = 0.008; χ 2  = 11.915, P = 0.001). The quality of life was improved in 4 patients and stable in 18 cases in treatment group, while no patient was improved and 13 were stable in control group (χ 2  = 9.669, P = 0.008). There was a significantly positive correlationship between the tumor burden and therapeutic effect (Kendall r = －0.765, P ＜ 0.001; Spearman r = －0.821, P ＜ 0.001). Conclusions Arsenic trioxide combined with TACE is an effective treatment method in treatiment of primary liver cancer and pulmonary metastases.