Objective To evaluate the sonographic features of benign symmetric lipomatosis (BSL).Methods The sonographic characteristics,including the affected area,boundary,capsule,growth pattern,internal echo,posterior echo,calcification,and blood supply,of 20 cases diagnosed with BSL by pathology were retrospectively analyzed.Results Accumulation of nonencapsulated fat tissue of all patients was depicted on sonogram.The fat deposits were ill defined and symmetrical,and most had no calcification within the lipomatous deposits.Fat deposits were predominantly seen in bilateral supraclavicular fossa (3 cases),bilateral supraclavicular fossa,and anterior part of the neck,infrahyoid region and suprasternal fossa (1 case),infrahyoid region (1 case),nape (1 case),juncture of the nape and chest-back (1case),groin area (3 cases),bilateral axillary fossa (2 cases),top of right shoulder (1 case),bilateral submandibular (1 case),left sternocleidomastoid region (1 case),bilateral breast (1 case),bilateral scrotal wall (1 case),left thigh (1 case),right upper arm (1 case),and right back near the spine (1 case).Color Doppler in the diseased regions showed that there was no or rare blood supply.Conclusions BSL have characteristic sonographic features.Ultrnsonography can clearly demonstrate the distribution of fat in the region and has great value in qualitative and quantitative diagnosis in BSL before operation.