The effects of topical GM1 ganglioside on crushed rat sciatic nerve regeneration were studied in this presentation. Thirty-four rats, with 68 bilateral sciatic nerves, were divided into seven groups: one group of four rats for measurement of normal motor nerve conduction velocity (MNCV), three as controls, and another three in the GM1-treated groups. Sciatic nerves were exposed and crushed at a site 6 mm distal to the sciatic notch by the standard technique. In this manner, 3 mm wide crush injuries were created. Then 2.1 microliters of normal saline was injected into the crush site in the control groups and an equal volume of GM1 solution (containing 10 micrograms GM1) was injected into the GM1-treated groups. Electrophysiological, histological, and morphometric evaluations were carried out at 12, 28, and 56 days. A significantly higher muscle action potential (MAP) rate was found in the GM1-treated group (70%) vs. the controls (none) at 12 days (P < 0.005), and increased MNCV was found in the GM1-treated groups at both 28 and 56 days, especially at 56 days, when it was 39.59 +/- 9.23 m/sec vs. 31.42 +/- 4.07 m/sec in controls (P < 0.05). Morphometrically, there were more regenerated myelinated fibers (RMFs) at 12 days, and larger diameter of RMFs were observed at 12, 28, and 56 days in the GM1-treated groups.