Objective To evaluate the efficacy and safety of ultrasound-guided ablation for portal vein tumor thrombus (PVTT) and to investigate the prognostic factors.Methods 50 patients with 54 PVTT underwent percutaneous ultrasound-guided ablation.The local treatment response,overall survival and complications were analysed.Results 50 (100%) patients successfully completed the ablation process.Major complication occurred in 1 patient (2%).41 (75.9%) of 54 thrombi achieved efficacious local therapeutic response.The overall survival rates at 1,12,24 and 36 months were 98.0%,49.7%,28.4% and 11.8%,respectively.On univariate analysis,liver function grading (P =0.011) and local therapeutic efficacy (P =0.015) were significant predictors of overall survival.On multivariate analysis,local therapeutic efficacy (P =0.002),liver function grading (P =0.018),age (P =0.028) and treatment method of PVTT (P =0.049) were significant predictors of overall survival.Conclusions Percutaneous ultrasound-guided ablation is a safe and efficacious therapeutic technique for PVTT.Prognostic factors of overall survival for PVTT after ablation were regional treatment efficacy,hepatic function grading,age and treatment method of PVTT.It is important to choose a proper treatment method for ablation. Key words: Hepatocellular carcinoma ; Portal vein embolism; Ultrasound-guide; Ablation ; Risk factors, prognosis