Twenty pairs of patients matched for sex, age, weight, and degree of trauma were treated either with an active Diapulse machine emitting pulsed, high-frequency electrical energy or with a non-active placebo machine. They were examined for swelling, pain, and disability before treatment and after three days under double-blind conditions. The results show that the pulsed, high-frequency electrical treatment has a definite biological effect on recently injured soft tissues, especially in the reduction of pain and disability.