The delay phenomenon has long been recognized as a powerful adjunct to flap surgery. Currently, delay procedures remain a reliable method of maximizing flap survival. Although delay yields successful results, the necessity of an additional surgical procedure is a persistent disadvantage from both clinical and economic perspectives. The authors' purpose is to demonstrate the usefulness of a novel chemical delay technique that obviates the need for a surgical delay procedure. This technique contains an epinephrine-loaded microsphere delivery system. In this study, 30 rats were subdivided into three groups of 10 animals. In group I, transverse rectus abdominis musculocutaneous (TRAM) flaps were delayed surgically 1 week before formal elevation. Group II (sham chemical delay) animals were injected with saline-loaded microspheres into the entire undersurface of the proposed TRAM flaps,;which were elevated 1 week later. In group III rats, epinephrine-loaded microspheres were injected into the undersurface of the TRAM flaps to initiate a chemical delay I week before surgical elevation. Groups were compared via TRAM flaps 1 week after elevation. There was a significant difference between groups I and III in favor of surface area viability and angiographic assessment (p < 0.05). Surgical delay has traditionally been accepted to be the most reliable method of enhancing flap viability. Statistically similar results were obtained by chemical delay initiated by epinephrine-loaded microspheres. Chemical delay is less invasive, less time-consuming, and far more cost-effective compared with its surgical alternative. The chemical delay model lends further support to the role of relative hypoxia as the primary promoter of the delay phenomenon.