Trivalidin, marketed by Milanese firm BRACCO, has been tested at the Department of Urology of the Budapest Medical University for 2 years and found to have a high tuberculostatic potency. Receiving daily doses of 750 mg, 50 patients showed essential improvement both subjectively and objectively and objectively. Laboratory analyses, cystoscopic pictures and roentgenograms made the subsidence of tuberculosis evident. Treatment with Terivalidin is promising also in cases of bilateral and solitary kidney tuberculosis. The drug enables the urologists to resort to conservative surgery in cases in which Terivalidin is promising also in cases of bilatgeral and solitary kidney tuberculosis. The drug enables the urologists to resort to conservative surgery in cases in which the patient responds only to Terivalidin so that, the urine having become negative, it is possible to eliminate the tuberculous focus (pole resection, cavernotomy). A case is described where, owing to the tuberculostatic effect of the drug, some 45 per cent of the diseased left kidney could be saved by adquate heminephrectomy. In another case the disappearance of juxtavesical ureteral stricture and the resulting improvement of the right kidney made it possible to extirpoate he destroyed left kidney. Neither of the two patients had complaints 12 months after the intervention; urinalysis, cystoscopy and all laboratory examinations gave normal values.