OBJECTIVE To analyze the causes of renal artery stenosis (RAS) and compare the clinical characteristics in accordance with the primary disease among patients aged from 30 to 50.METHODS Patients were grouped by etiologies of RAS.Groups were retrospectively examined and compared regarding demographic data,clinical manifestations,laboratory findings,and imaging findings.RESULTS A total of 152 patients (74 females,78 males;mean age: 40.70 ± 6.01 years) were enrolled,including 84 patients (55.3％) with atherosclerosis (AS),46 patients (30.3％) with Takayasu arteritis (TA),18 patients (11.8％) with fibromuscular dysplasia (FMD),and four patients (2.6％) with other etiologies.Patients in AS group had greater body mass index,higher prevalence of comorbidities and higher rate of smoking and drinking history.TA patients showed more constitutional symptoms and vascular findings,and higher erythrocyte sedimentation rate.RAS in both AS group and TA group mainly located on ostia and proximal segments,but RAS in FMD group mainly involved middle to distal segment of renal artery.The AS group had significantly lesser stenosis than the other groups.Although renal function evaluated by the estimated glomerular filtration rate did not significantly differ among the groups,the incidence of kidney shrinkage was significantly higher in the TA and FMD groups (39.1％ and 50％,respectively) than in the AS group (8.3％).The FMD group had milder cardiac damage than other groups.CONCLUSIONS AS was the most common cause of RAS in patients aged from 30 to 50,followed by TA and FMD.The etiology of RAS should be carefully distinguished based on clinical manifestations,laboratory findings,and imaging to ensure that proper treatment is provided.