Objective To study the clinical and X-ray findings in mamma virilis devolopment.Methods Clinical and X-ray findings in 11 patients with primary mamma virilis development were presented and analysed retrospectvely.Results X-ray findings were divided into 3 groups:1)mass(n=4):round or oval mass with high density and well-defined border;2)patch(n=4):patch like uneven mass with high density and ill-defined border;3)nodule(n=3):irregular uneven nodules.Conclusion Clinical and X-ray findings of mamma virilis development have some characteristic features,it can be differentiated from mamary cancer and pseudogynecomastia.