20 patients requiring casting for upper extremity injuries were randomized to receive either a waterproof liner or cotton liner in a fiberglass cast. Halfway through the treatment period, patients crossed-over and were treated with the other liner type. This study aimed to compare variables of comfort, skin condition, and patient preference between liner types. Results from this trial indicate that waterproof casting lowered the sweat and odor, though overall comfort was similar between cast liners. Patients (75%) displayed greater preference for the waterproof line.