BACKGROUND Renal calculi have been reported to occur in about 10% of patients with chronic sarcoidosis, but nephrolithiasis as a presentation of this disease has not been studied. METHODS The charts of 618 patients with histologically proven sarcoidosis, seen in the period October 1978-1992, were reviewed in order to identify nephrolithiasis at presentation. RESULTS Seventeen patients had renal calculi which preceded other manifestations of sarcoidosis. In six the occurrence of calculi suggested the diagnosis. Another eight patients had a previous history of recurrent colic with calculi. The time intervals between the first calculus and the appearance of other manifestations of sarcoidosis ranged from one to 25 years, but it was over four years in only two cases and all had at least one calculus in the year before the diagnosis was made. In the other three patients appearance of the calculus was distant in time and was probably unrelated to their sarcoidosis. In most cases the sarcoidosis was chronic and needed long term treatment with corticosteroids. Four patients had further calculi during follow up (one month to 16 years) due to an improper withdrawal of treatment decided by the patient in two cases, and to the reduction in the corticosteroid dose in the other two. CONCLUSIONS Calculi were the presenting feature of sarcoidosis in six (1%) patients, and were the first manifestation of the disease in a total of 14 (2.2%). This frequency is over 20 times the likely incidence of calculi in the general population. Renal calculi may therefore be a rare primary manifestation of sarcoidosis. In such cases the disease is likely to be chronic and to require long term corticosteroid therapy. Sarcoidosis should always be suspected in cases of nephrolithiasis of unknown origin.