Object To investigate the characteristics of reactive lymphoid hyperplasia after modified radical mastectomy with contrast-enhanced ultrasound(CEUS). Methods Thirty-five lymph nodes from 30 patients were studied both by conventional ultrasonographic techniques and by CEUS（gray scale,color Doppler,CEUS）. CEUS was performed with 2.4 ml intravenous bolus of contrast agent SonoVue and the results were registered with a software(Time-intensity curve).Atm,TtoPK,Grad were calculated and analysed.Results The average size of 35 lymph nodes were 1.25±0.68cm.Compare US and CEUS to conventional US,the accuracy were 85.7% vs 62.9%. The ultrasonorams of 28 cases were central enhancement,4 cases were peripheral enhancement,3 cases were both central and peripheral enhancement.The differences were statistically significant (P＜0.01). Time to arrival and time to peak were (16.4±6.3)s vs (23.4±7.9)s. Conclusions CEUS was the most accurate to characterize regional reactive lymph nodes after radical mastectomy. Enhancement pattern was centrifugal and homogeneous.