Objective：To compare the clinical safety of ultrasound ablation for uterine fibroids close to sacrococcyx with different models of high intensity focused ultrasound（HIFU） projection. Methods：92 patients with uterine fibroids received ultrasound ablation in our hospital from September 2008 to July 2009，and the distance from leiomyomas border to sacrococcyx was less than 30 mm on MRI images. All the patients were randomly divided into 2 groups. 47 patients in experimental group were treated under oblique HI－FU projection. 45 patients in controlled group were treated under vertical HIFU projection. Adverse events，visual analogue scale （VAS），and non-perfused volume （NPV） of both groups were evaluated in this study within a 6-month follow up.Furthermore，com－plications were assessed according to Society of Cardiovascular and Interventional Radiology（SIR） Classification. Results：92 cases successfully underwent one session of ultrasound ablation.No major complication was observed in all cases.The minor complication rate was significantly higher in the controlled group than in the experimental group（53.3% vs 36.2%；RR 1.71 [1.03-2.82]；P＜0．05）. VAS was also lower for the experimental group（2.9±1.4 vs 3.6±1.8，P＜0．05）. MRI performed 1 month after the treatment suggested that the experimental group obtained a greater NPV value（80.9%±18.9% vs 75.3%±18.2%，P＜0．05）. Conclusions：Ultrasound ablation for uterine fibroids close to sacrococcyx is safety and efficacy. Clinical strategy of oblique HIFU projection protocol reduces uncomfortable responses，pain and complica－tions

and improves tolerance and NPV value.