Considerable progress has been made regarding pathogenesis, diagnosis and conservative management of urolithiasis. The cause of the disease can now be determined in nearly 80% of the patients. New stone formation may be prevented in the majority of patients by selective medical treatment. The metabolic, physicochemical and clinical effects of diet, thiazides, allopurinol, sodium cellulose phosphate and potassium-sodium citrate (Oxalyt-C) are described in detail. Intrinsic problems involved in clinical trial with recurrent stone formers are discussed.