To explore therapeutic results of local microwave ablation for hepatic metastasis and the factors influencing the survival after percutaneous microwave ablation therapy. From July 1995 to June 2005 128 patients with 282 hepatic metastases nodules with the primary diseases of upper gastrointestinal tumor (n = 26), colorectal tumor (n = 44), breast carcinoma (n = 19), pulmonary carcinoma (n = 15), and malignant tumor in other part of the body (n = 24), underwent percutaneous microwave ablation therapy and were followed up for 29.7 +/- 19.9 months (1 - 103 months). The largest diameter of the metastatic nodules was 3.5 +/- 1.6 cm (0.7 - 8.6 cm). Sixty-four cases had 140 nodules 3.0 cm in diameter. Forty-seven patients had single nodule, 44 patients had 2 nodules, and 93 patients had 3 or more nodules. Fifty-seven patients had tumor of low differentiation, 53 had tumor of middle differentiation, and 18 had highly differentiated tumors. Kaplan-Meier method was used to calculate the cumulative survival rate. Statistical comparison of the effects of potential predictive factors on survival rate was performed using log-rank analysis. Multivariate analysis of the survival rates was performed by using Cox's proportional hazard model. The 1, 2, 3, 4, and 5-year cumulative survival rates of all 128 patients were 90.88%, 73.84%, 51.09%, 36.14%, and 31.89% respectively. Univariate analysis showed that tumor size (P = 0.028), tumor differentiation (P = 0.026) and local recurrence or new metastases (P < 0.001) significantly affected the survival. Multivariate analysis revealed that tumor size (P = 0.035), recurrence or new metastases (P = 0.001) and tumor differentiation (P = 0.038) each had a significant effect on survival. There is a significantly higher probability of long-term survival for patients with well-differentiated tumors 3.0 cm or less in diameter and without recurrence or new metastasis after percutaneous microwave ablation.