The present study examines the influence of ischemia on the muscle fibers and capillarization in rats. Muscle ischemia was achieved by a pneumatic tourniquet at a pressure of 300 mm Hg for 2, 4 and 6 h (groups I, II and III, respectively) to the right hindlimb above the knee. Numerous regenerative fibers were seen at 4 and, especially, 8 and 12 days after ischemia in groups II and III. The quantitative data revealed a significant decrease in the size of muscle fibers (regenerative fibers) in ischemic skeletal muscle, with a concomitant increase in fiber density. The capillary to fiber ratio shows a decrease at 4, 8 and 12 days after ischemia in the three experimental groups: in group I because of a decrease in capillary density; in groups II and III because of an increase in fiber density with respect to capillary density.