This article presents the spectrum of pelvic abnormalities in developmental diseases of bone. The pelvis comprises the ilium, ischium and pubis, and the sacrum. Knowledge of pelvic embryology and normal development is essential in recognizing pelvic abnormalities and disorders, which involve the number of bone elements, rate of ossification, density, and size or shape. Anarchic development of bone and dysplasias identifiable at birth must also be considered. The pelvis is important in the evaluation of such disorders because of the frequent, varied, and often specific radiologic abnormalities. The pelvis may also be the first evidence for a congenital malformation syndrome because it is often included in routine radiographic examinations.