Tubulointerstitial nephritis and uveitis (TINU) syndrome is a rare disease, often underdiagnosed or misdiagnosed in children. We describe the case of a 12-year-old boy who presented to Severance Hospital with a 1-month history of bilateral conjunctival injection. He was first evaluated by an Ophthalmologist in another hospital and diagnosed with panuveitis. Laboratory tests indicated renal failure, and a renal biopsy confirmed the diagnosis of acute tubulointerstitial nephritis. An extensive exclusion of all possible causes allowed a diagnosis of TINU syndrome. The patient was treated with a systemic corticosteroid (initially prednisolone, 2 mg/kg and later deflazacort 1 mg/kg) and topical steroid drops for 1 month. Azathioprine was later added to the treatment regimen and the systemic steroid was slowly tapered. The final outcome of renal-ocular disease was favorable in the patient. However, long-term follow-up is necessary to properly manage frequent relapses and incomplete renal recovery. TINU should be considered as a differential diagnosis in children with uveitis or acute renal failure.