Calyceal diverticulum is a relatively rare lesion that is usually asymptomatic but can assume clinical significance if drainage is impaired. Three patients are presented with unusual complications directly referable to a calyceal diverticulum. One child had a mobile calculus. In 2 others, intrarenal inflammatory masses developed in the area previously occupied by a calyceal diverticulum. One of these children had proved xanthogranulomatous pyelonephritis, and the other had an infected diverticulum.