AIM: To evaluate the efficacy of sequential use of transarterial chemoembolization (TACE) and percutaneous cryosurgery for unresectable hepatocellular carcinoma (HCC).METHODS: Four hundred and twenty patients were enrolled in this study.The patients, who were considered to have unresectable tumors due to their location or size or comorbidity, were divided into sequential TACE-cryosurgery (sequential) group (n =290) and cryosurgery alone (cryoalone) group (n =130).Patients in the sequential group tended to have larger tumors and a greater number of tumors than those in the cryo-alone group.Tumors larger than 10 cm in diameter were only seen in the sequential group.TACE was performed with the routine technique and percutaneous cryosurgery was conducted under the guidance of ultrasound 2-4 wk after TACE.RESULTS: During a mean follow-up period of 42 ± 17 mo (range, 24-70 mo), the local recurrence rate at the ablated area was 17% for all patients, 11% and 23% for patients in sequential group and cryoalone groups, respectively (P =0.001).The overall 1-, 2-, 3-, 4-and 5-year survival rate was 72%, 57%, 47%, 39% and 31%, respectively.The 1-and 2-year survival rates (71% and 61%) in sequential group were similar to those (73% and 54%) in cryo-alone group (P =0.69 and 0.147),54%) in cryo-alone group (P =0.69 and 0.147),while the 4-and 5-year survival rates were 49% and 39% in sequential group, higher than those (29% and 23%) in cryo-alone group (P =0.001).Eighteen patients with large HCC (> 5 cm in diameter) survived for more than 5 years after sequential TACE while no patient with large HCC (> 5 cm in diameter) survived more than 5 years after cryosurgery.The overall complication rate was 24%, and the complication rates were 21% and 26% for the sequential and cryo-alone groups,respectively (P =0.06).The incidence of hepatic bleeding was higher in cryo-alone group than in sequential group (P =0.02).Liver crack only occurred in two patients of the cryoalone group.CONCLUSION: Pre-cryosurgical TACE can increase the cryoablation efficacy and decrease its adverse effects, especially bleeding.Sequential TACE and cryosurgery may be the better procedure for unresectable HCC, especially for large HCC.