The development of a new rigid instrument for the exploration and treatment of pathologies localized above the ureteral orifice broadens importantly the field of urologie endoscopy. Heretofore, we have used this instrument in 12 patients for the study of various ureteral or renal pathologies. Its advantages over the flexible fiber optic ureteroscope and over the previous timid attempts of ureteroscopy or intraureteral litholapaxy with infantile cystoscopes are obvious. The operative possibilities of this instrument shall change the therapeutic approach to many upper urinary tract conditions.