To investigate whether red blood cell distribution width (RDW) is a marker of the risk of Henoch–Schonlein purpura (HSP) nephritis (HSPN), a total of 669 HSP patients and 168 healthy controls were included in this retrospective study. Two hundred fifty-six (38.3%) of the patients had kidney involvement. Compared with the HSP group, RDW was significantly higher in the HSPN group (P < .001). Binary logistic regression identified that HSPN was independently associated with age, RDW, platelet, and total cholesterol (odds ratio = 1.409, 1.353, 0.996, and 2.019, respectively). In addition, RDW values of HSPN patients with crescents on histopathology (classes III, IV, and V) were higher compared with those of HSPN without crescents (classes I and II) (P = .019). The receiver–operating characteristic curve analysis showed that the RDW at a cut-off point of 13.25 has 61% sensitivity and 79% specificity in predicting the presence of crescents on histopathology. It was first shown that RDW levels in HSPN are significantly higher than those in HSP without nephritis and healthy controls. RDW can be an independent predictor of HSPN and its levels greater than 13.25 were useful in the predicting the presence of crescents on histopathology.