In order to confirm the reliability of the sciatic functional index (SFI) in the rat, SFI, muscle strength, electrophysiological, and morphometric assessments were carried out from the 10th day to the sixth month after nerve injury or repair. The results showed that the SFI has a positive correlation with all tested indices of muscle strength, electrophysiology, and morphology (r = 0.925-0.996, P < 0.01 or P < 0.001). These results indicate that the SFI is a reliable index for evaluating rat sciatic nerve regeneration and can be widely used.