The effect of prolonged daily electrical stimulation (ES) on quadriceps strength in 22 patients during the 6 weeks following anterior cruciate reconstruction was investigated. Patients were randomly assigned to receive either a combination of ES and exercise or exercise alone. Isometric quadriceps strength was measured at the 7th, 8th, and 9th postoperative weeks. No significant difference in strength existed between the groups as a result of ES. A significant difference in strength did exist between competitive and recreational athletes regardless of treatment. Further research is needed to determine if the addition of ES to isometric exercise during immobilization can significantly retard strength loss after anterior cruciate reconstructive surgery.