BACKGROUND Renal manifestations are rare in Kawasaki disease (KD). Acute renal failure with tubular necrosis, tubulointerstitial nephritis and renovascular hypertension have been reported in KD, but only one case of a patient with KD associated with nephrotic syndrome (NS) has been reported to date, with the patient improving on steroid therapy but dying from coronary aneurysm. METHODS We report the cases of three children, aged 4, 4.5 and 8 years, respectively, who presented with typical KD symptoms (high fever, diffuse maculopapular rash, conjunctivitis, peripheral oedema, cervical adenopathies and high C reactive protein levels) and developed NS. RESULTS Patient 1 had a haemodynamic shock due to cardiac dysfunction and transient renal failure. Ten days later, he developed a NS which spontaneously disappeared 1 week later. Patient 2 had a NS on admission with normal plasma creatinine and no haematuria. Proteinuria disappeared within 10 days. Patient 3 developed NS 5 days after onset with a moderate increase in plasma creatinine. Proteinuria disappeared within 2 weeks. All three patients were treated with intravenous immunoglobulins, antibiotic therapy and aspirin, but none of them received steroid therapy. To date, all three patients have maintained long-term remission. CONCLUSIONS In conclusion, proteinuria with NS may develop during the acute phase of KD with persistent remission occurring without steroid therapy.