Freeze-thawed muscle grafts (FTMG) have been suggested as an alternative to nerve grafts in reconstruction of peripheral nerve defects. This study compares the results of immediate and delayed nerve repair with freeze-thawed muscle graft in a large animal model. Under general anaesthesia, ten adult sheep underwent excision of 3 cm of the right median nerve. Five had immediate nerve reconstruction with FTMGs (Group A) and five were repaired after 4 weeks (Group B). At 6 months, both the right (repaired) and left ("control") median nerves of each sheep were assessed. Nerve blood flow distal to the graft in both groups of repaired nerves was approximately 60% of that in their respective control nerves. Peak nerve conduction velocities were significantly slower in the repaired nerves. The mean fibre diameters of the immediate and delayed repairs were 5.06 and 3.90 mu respectively compared to a control mean of 8.58 mu. G-ratios confirmed that the repaired nerves in both groups were well myelinated. The authors conclude that the FTMG can be used in delayed as well as immediate nerve reconstruction with minimal impairment of final results.