Isaxonine is reported to accelerate the rate of peripheral nerve regeneration, stimulate axonal sprouting and promote motor and sensory function recovery. The target phenomenon in muscle fibers is the morphological expression of increased stretch activity in a diseased muscle. It can be produced in the gastrocnemius muscle of the rat by tenotomy and is inhibited by simultaneous denervation. The influence of isaxonine on this experimental model was studied. Twenty Wistar rats were submitted to bilateral section of the Achilles tendon and section of the left sciatic nerve. In ten rats, treated with isaxonine, the qualitative and quantitative changes in the gastrocnemius muscle were compared with the control group over a period of 3 weeks. No statistical differences were observed in the occurrence and inhibition of the target phenomenon, the muscle fibre size and the neuromuscular junction. Isaxonine has no direct effect on a diseased muscle with an intact nerve supply, nor in the early stages after complete denervation.