Crescentic IgA nephropathy (IgAN), defined as >50% crescentic glomeruli on kidney biopsy, is one of the most common causes of rapidly progressive GN. However, few studies have characterized this condition. To identify risk factors and develop a prediction model, we assessed data from patients ≥ 14 years old with crescentic IgAN who were followed ≥ 12 months. The discovery cohort comprised 52 patients from one kidney center, and the validation cohort comprised 61 patients from multiple centers. At biopsy, the mean serum creatinine (SCr) level ± SD was 4.3 ± 3.4 mg/dl, and the mean percentage of crescents was 66.4%± 15.8%. The kidney survival rates at years 1, 3, and 5 after biopsy were 57.4%± 4.7%, 45.8%± 5.1%, and 30.4%± 6.6%, respectively. Multivariate Cox regression revealed initial SCr as the only independent risk factor for ESRD (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.10 to 1.57; P=0.002). Notably, the percentage of crescents did not associate independently with ESRD. Logistic regression showed that the risk of ESRD at 1 year after biopsy increased rapidly at SCr>2.7 mg/dl and reached 90% at SCr>6.8 mg/dl (specificity=98.5%, sensitivity=64.6% for combined cohorts). In both cohorts, patients with SCr>6.8 mg/dl were less likely to recover from dialysis. Analyses in additional cohorts revealed a similar association between initial SCr and ESRD in patients with antiglomerular basement membrane disease but not ANCA-associated systemic vasculitis. In conclusion, crescentic IgAN has a poor prognosis, and initial SCr concentration may predict kidney failure in patients with this disease.