ObjectiveTo evaluate the clinical application and the efficacy of contrast enhanced ultrasonography (CEUS)guided percutaneous radiofrequency ablation (RFA) in patients with liver metastases. MethodsTotal 136 patients with 219 liver metastatic tumors, which were detected by CEUS before RFA therapy, were analyzed retrospectively. The diamter of tumors was (3.2±1.2) cm. Among them, the largest tumor more than 3 cm in diameter were found in 48.5% (66 patients), and 57.4% (78 patients) were with solitary metastasis. Enhanced CT and (or) MRI, and laboratory tests were applied to evaluate the outcomes after RFA treatment by regular followup. ResultsTumors were not detected by conventional ultrasonography in two cases, and 47.0% (63/134) of the patients with the largest tumor were 0.3 cm larger by CEUS than by conventional ultrasonography. More 40 tumors were detected in 18.4% (25/136) patients by CEUS. Followup ranged from 3 to 68 months (median time of 12 months). Early tumor necrosis rate one month after therapy was 98.2% (215/219 tumors). The incidence of local recurrence, new intrahepatic metastasis, and extrahepatic metastasis was 16.9% (23/136), 38.2% (52/136), and 8.8% (12/136), respectively. Local recurrence and new intrahepatic metastasis happened 2-25 months (median time of 6 months) after treatment. Local recurrence rates of the largest tumors ≥ 3 cm and tumor lt; 3 cm was 22.7% and 11.4%， respectively (P=0.079). The rate of new intrahepatic metastasis for the solitary metastasis cases was significantly lower than that for multiple metastases cases (25.6% versus 55.2%, P=0.000). The 1, 2, 3year survival rates were 82.5%, 64.3%, and 50.1%, and the 1, 2, 3year local recurrence free survival rates were 67.7%, 53.8%, and 38.3%, respetively. Patients with solitary metastasis survived longer than that with multiple metastases (P=0.034). ConclusionPatients with liver metastases treated by CEUSguided percutaneous RFA can get better survival rate, and CEUS is of much value for clinic application.