A 59-years-old male patient was admitted to our Service because of acute renal failure with maintained diuresis (creatinine at admittance 6.2 mg/dl), preceded by malaise and weight loss. Clinical examination was normal and no investigation lead to a sure differential diagnosis of acute renal failure. The only abnormal laboratory investigations were: marked hypercalcaemia (12.7 mg/dl), slightly depressed parathormone (10 pg/ml) and anemia (Hb 11.2 g/dl). Also instrumental investigations performed were inexpressive. The abrupt appearance of an unilateral 7th cranial nerve paralysis lead to start a steroid therapy followed, in some days, by the normalization of calcium level and by a partial improvement of renal function. A renal biopsy was finally performed which permitted the diagnosis of interstitial granulomatous nephritis according to a sarcoidosis disease. Steroid therapy was continued allowing to a progressive, although not complete, recovery of renal function. The case peculiarity consists of isolated renal lesions with a severe expression of renal disease. The absence of classical disease criteria (pulmonary involvement firstly), in our case total body Gallium-67 scintigraphy was normal, should not exclude the diagnosis of sarcoidosis. The authors underline the importance of renal biopsy in detecting interstitial renal lesions potentially leading to uremia.