This research investigated the effectiveness of low power laser irradiation (LPLI) with either a 632.8nm or 810nm laser in promoting regeneration of acutely transected corticospinal tract (CST) axons. Laser treatment was applied for 14 days, beginning immediately after CST lesion at vertebral level T9. At five weeks post-lesion, a fluorescent, anterograde tracer was injected into the motor cortex to visualize CST axons. Caudal to the lesion, non-irradiated control rats had significantly fewer axons (p<0.001) which regrew a significantly shorter distance (p<0.001) than rats treated with the 632.8nm or 810nm lasers. The 632.8nm laser treatment group had an average of 48.3 axons which regrew an average 9 mm past the lesion, while the 810nm laser treatment group had a significantly greater number of axons (138.7, p<0.05) which regrew 13.7 mm caudal to the lesion. Immunohistochemistry was used to show an increase in the number of cells labeling positively for ED1 (a marker for macrophages and activated microglia) and RP3 (a marker for neutrophils) in tissue treated with the 810nm laser vs. both the 632.8nm laser and non-irradiated tissue. Therefore, we found that LPLI with an 810nm laser was most effective in promoting axonal regrowth and promoting inflammatory cell invasion following CST lesion. This adds support to the possible use of LPLI as a non-invasive therapy for acute spinal cord injury.