High-voltage pulsed direct current (HVPC) has been shown to retard edema formation after impact injury in frogs, but the effectiveness of HVPC in reducing edema after other forms of trauma has not yet been established. The purpose of our study was to determine the effect of HVPC after simulated sprains. Hind limbs of 20 anesthetized frogs were injured by hyperflexing ankles to 90 degrees. Four 30-minute treatments were administered at 1.5-hour intervals. One limb of each subject was randomly selected to receive cathodal 120-Hz HVPC at voltages 10% lower than those needed to evoke muscle contraction. Limb volumes were measured by water displacement. ANOVA with repeated measures, Newman-Keuls post hoc tests, and selected t-tests were used to determine significance of limb volume changes. HVPC retarded edema formation. HVPC was so effective (p less than .0001) that significant differences between treated and untreated limb volumes were evident after the first treatment (p less than .01), and these differences remained throughout a 17-hour posttreatment period.