The "string sign" is a physiological and reversible response of the internal mammary artery (IMA) anastomosed to a moderately stenotic coronary artery. We describe a patient who presented postoperatively with a string sign phenomenon of the right branch of the lambda-composite graft. The graft regained full patency 32 months after the surgical procedure with progression of the native coronary artery stenotic lesion. This case demonstrates that under specific conditions, such as the progression of native coronary artery disease, a no-flow composite graft employing IMAs can only regain patency and functional status in the same way as in situ IMAs. These findings confirm that the IMA remains the conduit of choice not only for its long-term patency, but also for its physiological adaptation characteristics.