Utilizing a sciatic nerve-transection model in rats, we studied the collagen content of normal control nerves, the long-term collagen accummulation in the distal stump of the transected nerve, the content of collagen of the posterior tibial nerve distal to the transection, and the myofibrosis of the gastrocnemius muscle. The distal stump of the sciatic nerve accumulated significant amounts of collagen with time but the posterior tibial nerve at a distance from the site of transection showed no progressive collagen accumulation. The histologically evident myofibrosis of the denervated gastrocnemius muscle was shown to be the result of a selective loss of muscle elements and not of an accumulation of collagen. cis-Hydroxyproline, a proline analogue, limited neuroma formation following neurorrhaphy. The findings suggest that the results of delayed repair of nerves should not be impaired by intraneural scarring if enough of the transected nerve beyond the point of intraneural scar formation is resected.