Effects of two stable TRH analogs were compared after experimental spinal trauma in cats. CG3509, which has a substitution at the amino-terminus of the peptide, improved neurologic recovery; MK771, which has modifications at both ends of the tripeptide, was ineffective. These findings indicate that TRH analogs may be of use in spinal cord injury, and suggest that the C-terminal amino acid may be critical for the beneficial effects of TRH or TRH-analogs in CNS injury.