[Duplication of the gallbladder. A rare anomaly, more often a diagnostic error (author's transl)].

A case of true duplication of the gallbladder and three cases with roentgen signs simulating duplication are reported. In true duplication the diagnosis was made by routine cholecystography which showed a double gallbladder with ductular shape. In three cases the cause for an incorrect diagnosis by cholecystography were an ampullary right renal pelvis visualized by heterotopic renal excretion of the contrast medium, a short loop of the first and second part of the duodenum and a diverticulum at the outer border of the duodenum.