Six cases of chronic renal failure related to granulomatous renal sarcoidosis are reported and compared with data in the literature. The particular features of sarcoidosis granulomatous interstitial nephritis should be emphasised because presentation may be misleading. Renal failure usually presents with a rapidly progressive course, either isolated or associated with mild proteinuria and sterile leukocyturia, while extrarenal localisations may be absent. Diagnosis should be suspected on the basis of elevated or paradoxically normal serum calcium concentrations, due to increased plasma concentrations of calcitriol, while immunoreactive circulating parathormone concentrations are depressed. Calcitriol as well as angiotensin-converting enzyme could represent unregulated secretion products from granulomatous tissue and their plasma concentrations may roughly reflect activity of the disease. Early corticosteroid treatment dramatically improves renal function but long-term renal prognosis may be oblitered due to progressive chronic renal failure related to fibrosis scarring.