A protective cover for a cast. Exemplary embodiments include a cover for a lower arm cast including an optional thumb cover. Exemplary embodiments may be constructed from resilient foam located within a protective shell, and the protective shell may include fasteners arranged to retain the cast cover around the cast. An exemplary thumb cover includes a plurality of pockets, each of which holds a thumb pad. The exemplary thumb cover may be installed on the cast prior to installing the cast cover, and the thumb cover may extend through an opening in the cast cover.
