Objective To compare microendoscopic discectomy (MED) with open discectomy (OD) for degenerative lumbar spinal stenosis in terms of cl inical outcomes, and provide experience and therapeutic evidence for cl inical appl ication.Methods From May 2002 to October 2007, 215 patients with lumbar spinal stenosis were randomized into two groups, and underwent either MED or OD. In group A, 105 patients underwent MED, including 56 males and 49 females aged 34 to 83 years old (average 45 years old); the duration of the disease ranged from 9 months to 26 years (average 50 months); the spinal stenosis involved one segment in 76 cases, two segments in 27 cases, and three segments in 2 cases. In group B, 110 patients received OD, including 57 males and 53 females aged 35 to 85 years old (average 47 years old); the duration of the disease ranged from 8 months to 25 years (average 48 months); the spinal stenosis involved one segment in 78 cases, two segments in 29 cases, and three segments in 3 cases. No significant difference was evident between two groups in terms of the general information(P gt; 0.05). Results Operation was successfully performed in all cases. Volume of intraoperative blood loss was (82.14 ± 6.18) mL in group A and (149.24 ± 11.17) mL in group B. Length of hospital stay was (7.0 ± 2.1) days in group A and (12.0 ± 2.6) days in group B. Significant difference was noted between two groups in terms of the above parameters (P lt; 0.01). All the wounds healed by first intention. The patients were followed up for 13-54 months (average 27 months) in group A and 12-55 months (average29 months) in group B. Four patients in each group suffered from spinal dural rupture during operation and recovered after corresponding treatment. Three patients in group B had lumbar instabil ity 3 years after operation and recovered using lumbar interbody fusion combined with general spine system internal fixation. No such compl ications as wrong orientation, nerve root injury, cauda equina injury and infection occurred in each group, and radiology exam showed no relapse. Therapeutic effect was evaluated by Nakai standard, 52 cases in group A were graded as excellent, 45 as good, 7 as fair, 1 as poor, and the excellent and good rate was 92.4%; 53 cases in group B were graded as excellent, 48 as good, 8 as fair, 1 as poor, and the excellent and good rate was 91.8%; there was no significant difference between two groups (P gt; 0.05). Conclusion Two methods have the similar therapeutic effect, but MED el iminates the shortcomings of traditional OD, so it is one of ideal minimally invasive operative approaches for degenerative lumbar spinal stenosis.