A new pulsed radio frequency electric field pattern evolved from bone studies was adopted to accelerate fracture healing in rats. The output of a specially designed signal generator was ca-pacitatively coupled to the fracture site using a pair of stainless steel electrodes. In a series of experiments performed on rats, fractures were induced in the femoral shafts and electrical stimulations were applied to one leg. Bone mass formed in the gap was estimated by measurement of the cortical thickness and by ultrasonic attenuation. We found that the stimulated side showed greater bone mass than the contralateral control. We suggest that. this device offers a simple and reliable method of acclerated healing, immediately after fracture. © 1991 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.