Objective: To compare posterior cranial fossa measurements in patients with & without Chiari I malformation; and determine if there is a correlation between cerebellar tonsillar descent in patients with and without Chiari I malformation and five skull morphometric measurements: clivus length, anteroposterior diameter of the foramen magnum, and Boogard's angle, supraocciput length, anteroposterior diameter of posterior cranial fossa.