Abstract Background and Aims Lupus nephritis (LN) is a common and severe complication of childhood-onset SLE. Little is known about the long-term renal outcome of childhood-onset LN. We investigated predictive factors of end-stage kidney disease (ESKD) and chronic kidney disease (CKD) in a paediatric cohort of patients with LN. Method This is a retrospective multicentre study including patients with childhood-onset (<18 years) biopsy-proven LN. Clinical features were analysed at disease onset, time of kidney biopsy, 12 and 24 months after biopsy, and last follow-up. We investigated the prognostic significance of clinical, laboratory and histologic characteristics on the incidence of ESKD and CKD stage 3-5. Results We included 73 patients with a median age of 14 years (IQR 11.5-17) . At the time of kidney biopsy, most subjects displayed an aggressive disease: 2 (3%) children required haemodialysis, 27 (38%) had an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. The overall median eGFR was 70 mL/min/1.73 m2 (IQR 43-96) . Moreover, the median proteinuria was 4 g/24 h (IQR 1.35-7.41) , with 41 (59%) children displaying a nephrotic range proteinuria (i.e., >3 g/24 h) . The median follow-up was 13.3 years (IQR 4.7-25.4) . A total of 10 patients (13.7%) reached ESKD, the majority of whom (12%) within 10 years from kidney biopsy; during the subsequent follow-up the incidence of ESKD stabilised (Fig. 1). At last follow-up, around 50% of patients displayed an eGFR <90 mL/min/1.73 m2. A younger age at LN onset, a lower eGFR and central nervous system involvement at the time of kidney biopsy were identified as predictors of ESKD by a univariable Cox regression model (Table 1). The same features were significantly associated with the occurrence of CKD stage 3-5 at last follow-up at a univariable logistic regression analysis. Conclusion LN often presents with severe kidney function impairment and aggressive systemic involvement in children. In our cohort, whose follow-up was among the longest reported in the literature, 12% of patients reached ESKD within 10 years from kidney biopsy. Significant predictors of poor kidney outcome in the long term were a younger age at LN onset, a lower eGFR and the presence of neurological manifestations at the time of kidney biopsy.