Little has been written about the pathogenesis of pes cavus in Charcot-Marie-Tooth disease (CMT). In 12 of 22 patients in a family with known autosomal dominant CMT, a predictable pattern of progression was related to a centrifugal pattern of innervation of the extremity. The gait pattern had greater complexity than the steppage gait. Pelvic shift and elevation on the swing side were used to clear the "drop foot" from the floor. Lateral flexion of the trunk to the opposite direction was used for balance. Previous descriptions of the etiology of pes cavus did not apply to this family. The mode of development of pes cavus in CMT is not known and requires further investigation.