Ordered differential display PCR was used to identify differentially expressed genes in rat dorsal root ganglia at 7 days following chronic constriction injury (CCI) of the sciatic nerve. Fourteen differentially displayed cDNA bands were isolated, cloned and verified by RT-PCR. The four mRNAs were increased, which included mRNAs encoding heat shock protein 27, fatty acid binding protein, apolipoprotein D and one novel gene. Six down-regulated clones were microtubule-associated protein 1B, protein tyrosine phosphatase alpha, Kv1.2 channel, myelin protein SR13, medium-sized neurofilament protein, and one novel gene. Our results show that many differentially regulated genes after CCI may play a role in nerve degeneration and/or regeneration and provide a molecular framework for understanding the peripheral mechanism underlying neuropathic pain.