A young woman had unilateral dermatomal hyperhidrosis documented by a starch-iodine technique. Evaluation failed to reveal any associated causative conditions. She was treated with 20% aluminum chloride hexahydrate solution in absolute alcohol (Drysol) with a favorable response. With recurrent use, however, she developed miliaria following exertion. Aluminum chloride hexahydrate was shown to be an effective agent to treat this unusual condition, but miliaria with exertion secondary to its use may be a limiting factor.