Enthusiastic reports about percutaneous intradiscal laser nucleotomy have been encouraging to neurosurgeons treating patients with intervertebral disc herniation. Since high energy is transmitted to deep tissue and the procedure is not able to be visualized unless done endoscopically, we designed this experimental study on cadaveric sheep lumbar discs to determine the physical and neuroradiological effects of laser irradiation, altering the joules of energy applied, as well as output power, and pulse interval and number. Intradiscal pressure fell during the irradiation procedures. Very high temperatures were recorded at the neural foraminae when high laser energy levels were used, these specimens showed macroscopic thermal changes in the nearby neural tissue. The vacuum phenomenon, representing vaporization of the disc, was better visualized using computerized tomography than magnetic resonance imaging.