Acutely sprained ankles represent a frequent and common injury among active duty troops in training, and are a significant source of morbidity with respect to days lost to training. Swelling in the form of periarticular edema limits motion, causes pain, prevents wearing of normal foot gear, and slows the healing process. Reduction of edema was attempted in acutely sprained ankles by the use of pulsed electromagnetic energy (Diapulse). In a randomized, prospective, double blind study of 50 grade I and II (no gross instability) sprained ankles, a statistically significant (p < 0.01) decrease in edema was noted following one treatment with Diapulse. The application of this modality in acutely sprained ankles could result in significant decreases in time lost to military training.