The changeability in the gene expression for five species of fatty acid binding protein (FABP) was investigated in the crushed hypoglossal nucleus by in situ hybridization histochemistry. Increased gene expression for skin-type fatty acid binding protein (S-FABP) was evident in the affected hypoglossal neurons on the 3rd day after nerve crush, and it lasted until the postoperative day 14. On the other hand, no significant gene expression for heart-, liver-, intestinal- or brain-type FABPs was detected in the hypoglossal neurons of normal control or in these neurons for 3 weeks after the nerve crush. These findings suggest that skin-type FABP may selectively contribute to some important roles in morphological and biochemical changes of neuronal cells associated with the nerve regeneration.