Among 3279 urographies, double renal pelvis was encountered in 49 cases (1.5%). In 10 cases ureteral calculus occurred on the same side as the double pelvis. When the stone is situated in the common ureter, the excretion of contrast medium is compromised in the entire kidney. In a single instance, the 2 excreting portions were revealed on the nephrogram. A stone in one of the branches of a double ureter will cause a delayed secretion, or an accumulation of contrast medium in the renal parenchyma corresponding to the occluded branch. No facts whatever have been revealed in support of the existence of a homolateral reflex calculus anuria to the non-affected portion of the kidney.