Following spinal cord injury, the expiratory muscles develop significant disuse atrophy characterized by reductions in their weight, fiber cross sectional area and force generating capacity. We determined the extent to which these physiological alterations can be prevented with electrical stimulation. Since a critical function of the expiratory muscles is cough generation, an important goal was the maintenance of maximal force production. In a cat model of spinal cord injury, short periods of high frequency lower thoracic electrical spinal cord stimulation (SCS) at the T10 level (50 Hz, 15 min., twice/day, 5 days/week) were initiated 2 weeks following spinalization and continued for a 6 month period. Airway pressure (P) generating capacity was determined by SCS. Five acute, spinalized animals served as controls. Compared to controls, initial P fell from 43.9 ± 1.0 to 41.8 ± 0.7 cm H₂O (NS) in the chronic animals. There were small reductions in the weight of the external oblique, internal oblique, transverses abdominis, internal intercostal and rectus abdominis muscles (NS for each). There were no significant changes in the population of fast muscle fibers. Since prior studies (31) have demonstrated significant atrophy following spinalization in this model, these results indicate that expiratory muscle atrophy can be prevented by the application of short periods of daily high frequency stimulation. Since the frequency of stimulation is similar to the expected pattern of clinical use for cough generation, the daily application of electrical stimulation could potentially serve the dual purpose of maintenance of expiratory muscle function and airway clearance.