Objective : The authors have developed a procedure, termed posterior microscopic lesionectomy, that creates a minimal laminotomy site according to the location of the shifted disc using the $METRx^{TM}$ system in the lumbar spine. This study compared the usefulness and surgical outcomes of this procedure with those of traditional standard lumbar discectomy. Methods : From June 2003 to June 2004, Twenty-two patients with one-level radiculopathy due to lumbar disc herniation underwent posterior microscopic lesionectomy with the assistance of an operating microscope and the $METRx^{TM}$ tubular retractor. Surgical results of the new procedure were compared to those of 39 patients who underwent traditional lumbar discectomy from April 2003 to September 2004. All patients were evaluated for pain score, clinical assessment according to the VAS, and Roland-Morris scores pre-operatively and at 1, 3, 6, and 12 months post-operatively. Results : Mean blood loss, operation time, and admission date showed significant improvements for microscopic lesionectomy compared to traditional lumbar discectomy [P < 0.001]. Also, both measures of short-term functional improvement, the Visual Analogue Scale[VAS] and Roland-Morris[RM] scores, were statistically better for microscopic lesionectomy than for traditional discectomy [P < 0.001]. Conclusion : Posterior microscopic lesionectomy can be performed more safely and provide greater benefit than traditional discectomy. The procedure is associated with less post-operative pain, shorter hospital stays, and quicker rehabilitation.