Abstract: Objective: To investigate the effect and toxicity of high intensity focused ultrasound(HIFU) combined with chemotherapy for recurrent or metastatic peritoneo-pelvic malignant tumors.Methods: Sixty-eight patients with history of surgical treatment or chemoradiotherapy and clear patho-logical diagnosis in the anamnesis of recurrent or metastatic peritoneo-pelvic malignant tumors were randomly divided into two groups. HIFU plus chemotherapy were administrated to the patients in thestudy group (n=36), and chemotherapy alone in the controls (n=32). All patients received at last two cy-cles of chemotherapy and were followed up for more than 1 year. Results: The overall response rateand clinical benefit rate (CBR) were 69.4% and 83.3% in the study group, 31.3% (P<0.01) and 56.3%(P<0.05) in the control group. The mean survival time were 9.1± 3.1 months and 6.8± 2.4 months respec-tively (P<0.01). The main toxicities included myelosuppression and gastrointestinal reaction (P>0.05).Other side effects, such as the viscera perforation, massive hemorrhage, pancreatic leakage and peri-tonitis didn't occur in the study group. Conclusion: The results indicate that HIFU with chemotherapyis a feasible and well-tolerated regimen on recurrent or metastatic peritoneo-pelvic malignant tumors.