Antibiotic delivery into areas of poor vascularity is decreased or absent due to scarring and decreased local blood supply despite adequate drug concentration in the blood. To determine the antibiotic carrying capacity of a transferred muscle flap into a fibrotic cavity we undertook an experimental study using a tissue cage model in rabbits. Bilateral fibrotic cavities were created over the dorsal thorax in New Zealand rabbits by inserting silastic tubes. Three months later a vascularized 4 × 5 cm strip of trapezius pars thoracic muscle was placed into the anterior end of the fibrotic cavity on the right side of each animal. Cavity serum samples were withdrawn from both the experimental and control sides at definite times after antibiotic i.m. injection. Blood and chamber fluid antibiotic levels were determined after hind limb injection of different classes of antibiotics with different protein binding up to 12 weeks following muscle transfer. This study suggests that muscle flaps do increase the concentration of antibiotics which can be achieved within a fibrotic cavity. Antibiotic delivery is decreased with time due to increased scarring around the muscle.