Objective: To study the MRI signal changes of hysteromyoma before and after treated by high-intensity focused ultrasound (HIFU), evaluate the effects of HIFU treatment and providing the reference for clinical therapy. Methods:MR scan and enhanced-scan were performed by GE SignaHDe 1.5T MR system on 83 patients with hysteromyoma (a total of 117 myomatas) before and after HIFU treatment within one week. Through the observation of whether there were coagulation necrosis and blood supply diminution to evaluate the effects of HIFU treatment. The appearance of coagulation necrosis and blood supply diminution meant a remarkable therapeutic effect, and vice versa. Results:By analyzing the MR images of 83 patients with hysteromyoma (a total of 117 myomata) treated by HIFU from March 2012 and November 2012, we found that 106 myomata’s MRI signals clearly changed, from low signal to slightly high or equal signal on T1WI, from low signal to low or slight high signal on T2WI, which meantcoagulation necrosis and blood supply diminution. Besides, the rest 11 myomata’s MRI signal showed no changes before and after HIFU treatment on both coagulation necrosis and blood supply diminution. Conclusion:MRI is the most effective methods on evaluating the effects of HIFU treatments.