The slow Wallerian degeneration mouse, C57BL/Wld(s), carries a dominant mutation that delays Wallerian degeneration in the distal stump of an injured axon. The protective gene has been identified and also found to protect axons from the neurotoxin vincristine. Therefore, it is important to determine whether it has a widespread application to protect axons in neurological disease. In principle, this can be done by crossing Wld(s) to neurological mutant mice, but first a method is needed to track the inheritance of the neuroprotective Wld(s) allele. Due to the complex nature of the mutation, there is no simple method to distinguish Wld(s) homozygotes, heterozygotes and wild-type mice. Therefore, we report a genotyping method for Wld(s) based upon pulsed field gel electrophoresis (PFGE) and compare it with the alternatives of PCR and Southern blotting. The effect of the Wld(s) mutation on axon degeneration in diverse inherited pathologies, and the consequence for symptoms, can now be investigated.