The effects low-level laser therapy on the regeneration of compression neuropathy were studied in the rat's sciatic nerve. In 30 rats divided into 3 groups, both sciatic nerve were surgically exposed and mechanically compressed. The study groups, meaning the right sciatic nerve, was treated with 4.3mW-632.2nm-continuous wave of He-Ne laser and 4.6mW-850nm-plused of GaAIAs laser irradiation for 5 min. per day during a 10 or 20 or 30 days after compressed injury. The control group, meaning the left sciatic nerve, was observed without any treatment.

At the end of immediately, 10, 20, and 30 days, the sciatic nerve was mechanically compressed, and the latency and amplitude of the compound motor action potentials were measured with a Medeles MS 20 Mystro, The weight of gastrocnemius muscles were measured by the elect개n scale of a Sartorius DJ-2105, Then the study groups and the control groups were compared every third period. The data obtained form 30 rats were statistically analyzed by paired t-test and one way ANOVA.

The regeneration of compression neuropathy of the study groups was not significant in the latency and amplitude in the nerve conduction study, when compared with those of the control groups after 10, 20, 30 days.

The myelin sheath of the sciatic nerve on the electron microscopy was not signfifcantly thickened in the study groups, when compared with those of the control groups after 20 and 30 days, but showed only significant thickened myelin sheath after 10 days.

The weight of the gastrocnemius muscles in the study groups were significantly(p<0.005) higher,when compared with those of the control groups.

If modified and supplemented the laser irradiation techniques or methods, the low-level laser therapy seems to have had an minimal effect to regeneration process of compression neuropathy in rats.