Strabismus surgery sometimes fails because of the mechanical restriction caused by the development of fibrous adhesions between the operated muscle and the surrounding tissues. Reoperation increases the frequency and severity of mechanical restriction significantly because of additional scar formation. Attempts to isolate the muscle from other tissues using gelatin sponges or Supramid plastic sleeves have been unsuccessful because of the body's reaction to these permanent foreign bodies. We used an ultra-pure fraction of sodium hyaluronate to study whether this nonantigenic, noninflammatory, viscoelastic substance could function as a temporary sleeve to prevent or reduce scarring and mechanical restriction following strabismus surgery. We resected the superior rectus muscle of 14 eyes from seven 5- to 7-pound white rabbits. In one eye, we instilled sodium hyaluronate 1% around the muscle. The other eye served as a control. The rabbits were killed at five, seven, ten, 14, 21, 28, and 42 days. Ante mortem length-tension measurements and post mortem histologic examinations of the operated muscles were performed in a blinded fashion. The results suggested, but did not definitely demonstrate, that sodium hyaluronate may reduce postoperative adhesions.