Predictive factors of renal involvement or relapsing disease in children with Henoch-Schönlein purpura (HSP) are poorly known. We examined clinical and laboratory variables concerning HSP evolution in children hospitalized in the last decade to predict the possibility of renal complications or relapse occurrence. Periodic clinical evaluations with urinalysis were performed for 6 +/- 3.6 years. Simple logistic regression showed that persistent rash and severe abdominal pain at the onset of HSP are significantly related to renal involvement, while persistent rash is significantly related to relapsing disease. Multiple logistic regression showed that persistent rash remains related to renal involvement when adjusted for sex, age, and severe abdominal pain and conversely that severe abdominal pain is not related to renal involvement when adjusted for sex, age, and persistent rash. In conclusion, persistent rash over a period longer than 1 month seems to represent a significant predictor of renal sequelae and disease relapse in children with HSP.