Microendoscopic discectomy (MED) is an established procedure used to treat lumbar central spinal stenosis (LCSS) and lateral recess stenosis (LRS). The Interlaminar Endoscopic Surgical System iLESSYS® Delta approach has been developed from the traditional interlaminar endoscopic technique for the treatment of LCSS and LRS. In the present study, MED was used as a reference to evaluate this newly developed approach. A total of 82 and 52 patients with radicular leg pain and/or neurogenic claudication symptoms were treated by spinal canal decompression using the MED or iLESSYS® Delta approach, respectively. The clinical outcomes of the patients were analyzed using the Modified MacNab's criteria, visual analogue scale (VAS) leg pain score, VAS back pain score and the Oswestry Disability Index (ODI) score. Finally, the effectiveness of the decompression was evaluated on a cross-sectional area of the dural sac (CSAD) at the disc level. The incision length in the iLESSYS® Delta group was significantly decreased compared with the MED group (P<0.05); however, the duration of the operation in the iLESSYS® Delta group was significantly longer compared with the MED group (P<0.05). The VAS score of the back and ODI score in the iLESSYS® Delta group were significantly decreased compared with the MED group at the 1-week follow-up (P<0.0125). The postoperative CSAD was also significantly increased in both groups compared with before the operation (P<0.05); however, there were no significant differences in the postoperative CSAD between the two groups. The good-to-excellent rates of the MED and iLESSYS® Delta approach were 89.0 and 90.4%, respectively, whereas the complication rates of the MED and iLESSYS® Delta system were 3.66 and 3.85% in the two groups, respectively. In conclusion, the iLESSYS® Delta approach was identified to be comparable with the MED approach for treating LCSS and LRS, demonstrating both precise and limited decompression. In addition, the iLESSYS® Delta approach may reduce the short-term back pain and promote faster recovery compared with the MED. Copyright: © Wu et al.