Renal lithiasis is a significant medical and social problem. Worldwide recurrence is anywhere from 3% to 5%. Objective of this paper is to evaluate two methods for distinguishing between stone formers and non-stone formers. Urine samples were titrated with calcium and seed crystals were added to facilitate precipitation. Ionic calcium levels were monitored and compared between the two groups. Stone formers showed impaired tolerance to the calcium added and increased precipitation on seed crystals. Both methods discriminated between stone formers and non-stone formers. Further evaluations are needed to establish the better of the two for wider clinical use.