In experienced hands, high-resolution real-time sonography has been shown to be an accurate noninvasive method for diagnosis of rotator cuff tears. The sonographic appearance of the postoperative rotator cuff has not been previously reported. Forty postoperative patients were studied sonographically 1 week to 6 years after rotator cuff repair. The postoperative rotator cuff is abnormally echogenic and can be very similar in appearance to a small rotator cuff tear in a nonoperated patient. Soft-tissue planes about the tendon are distorted or absent. Criteria for diagnosis of retear must be different from those used in detecting new tears in a nonoperated cuff. Postoperative echogenicity is normal, but the finding of a defect or gap within the rotator cuff tendon is the only accurate sign of a recurrent rotator cuff tear.