The main aim of this study was to evaluate the relationship between obesity and renal involvement in children with Henoch-Sch(o)nlein purpura (HSP).A retrospective study of 141 pediatric patients with HSP was conducted in our hospital.The clinical data of all patients were collected from the electronic medical record management system from January 2010 to June 2014.The possible risk factors of renal involvement, especially obesity, were analyzed using univariate and multivariate analyses.Renal involvement occurred in 45/141 of the patients.A univariate analysis showed that an age more than 7 years at onset, persistent purpura, obesity, time from symptoms onset to diagnosis more than 14 days, and decreased C3 all increased the risk of renal involvement in HSP.The forward stepwise logistic regression analysis indicated obesity (odds ratio (OR) 4.43, 95 % confidence interval (CI) 1.896 to 10.358), age more than 7 years at onset (OR 2.81, 95 % CI 1.142 to 6.907), and persistent purpura (OR 2.57, 95 % CI 1.119 to 5.909) were independent risk factors for renal involvement.Conclusions: Our results show that obesity can increase the hazard of renal involvement in children with HSP and reconfirm that older age at onset and persistent purpura are the independent risk factors for renal involvement.