The rat gastrocnemius muscle can serve as a vascularized, innervated muscle transplant model. To establish the anatomic and technical details of this model, we performed ten gastrocnemius transplants and collected data on muscle weight, dimension, and vessel caliber from each muscle. The muscle, consisting of medial and lateral heads, is supplied by pairs of sural vessels averaging 0.2 mm in diameter. These vessels, however, can be taken in continuity with the femoral vessels (averaging 1.0-1.6 mm in diameter), which are used for transplantation. The muscles weighed an average of 2.8 g, and the average pedicle length was 24 mm. Eight of ten transplanted muscles were viable with intact circulation at 72 hr. The gastrocnemius transplant was technically reliable, and the muscle bulk and contour could allow biochemical and functional studies. Donor site morbidity limits this model to transplantation studies.