Objective <p>To compare the clinical efficacy and radiological outcomes of the far lateral approach of uni-portal non-coaxial spinal endoscopic surgery versus traditional percutaneous endoscopic transforaminal discectomy (PETD) for the treatment of L5/S1 foraminal stenosis with a high iliac crest.</p> Methods <p>A retrospective analysis was conducted on 82 patients with L5/S1 foraminal stenosis and a high iliac crest treated at our hospital from June 2023 to June 2025. Patients were divided into a uni-portal non-coaxial spinal endoscopic surgery group (<i>n</i> = 42) and a PETD group (<i>n</i> = 40) based on the surgical procedure. Operative time, the fluoroscopy time estimated blood loss, length of hospital stay, and complication rates were recorded and compared between the two groups. Clinical outcomes were evaluated using the Visual Analogue Scale (VAS) for leg pain, the Oswestry Disability Index (ODI), and the modified MacNab criteria. Radiological assessments included postoperative foraminal area, facet joint preservation rate, and segmental stability.</p> Results <p>All patients were followed up for at least 12&#xa0;months. The uni-portal non-coaxial spinal endoscopic surgery group had a significantly shorter operative time (68.5 ± 12.3&#xa0;min vs. 92.6 ± 18.4&#xa0;min, <i>P</i> &lt; 0.001) and significantly fewer fluoroscopy time (5.4 ± 1.5 vs. 15.8 ± 4.2, P &lt; 0.001) compared to the PETD group. There were no significant differences between the two groups in estimated blood loss (42.5 ± 15.3&#xa0;mL vs. 40.2 ± 16.1&#xa0;mL, P 0.05) or length of hospital stay (3.2 ± 1.1&#xa0;days vs. 3.6 ± 1.4&#xa0;days, P 0.05). Both groups showed significant improvement in VAS and ODI scores at all postoperative time points compared to preoperative values (<i>P</i> &lt; 0.05). At one&#xa0;week postoperatively, the uni-portal non-coaxial spinal endoscopic surgery group had noticeably better leg pain VAS scores than the PETD group (2.2 ± 0.7 vs. 3.3 ± 1.3, <i>P</i> &lt; 0.01), while clinical outcomes were comparable between the two groups at three, six and 12&#xa0;months postoperatively (P 0.05). The excellent-to-good rate according to the modified MacNab criteria was 90.5% in the uni-portal non-coaxial spinal endoscopic surgery group and 87.5% in the PETD group (P 0.05). Radiologically, the uni-portal non-coaxial spinal endoscopic surgery group demonstrated a noticeably larger postoperative foraminal area (79.8 ± 13.2 mm² vs. 63.5 ± 12.1 mm², P &lt; 0.001) and a noticeably higher facet joint preservation rate (93.5% vs. 75.8%, P &lt; 0.01) compared to the PETD group. The complication rate was 7.1% in the uni-portal non-coaxial spinal endoscopic surgery group and 17.5% in the PETD group (P 0.05).</p> Conclusion <p>Both the far lateral approach of uni-portal non-coaxial spinal endoscopic surgery and PETD are effective treatments for L5/S1 foraminal stenosis with a high iliac crest, yielding satisfactory clinical outcomes. Compared to PETD, uni-portal non-coaxial spinal endoscopic surgery offers advantages including shorter operative time, less fluoroscopy, more thorough foraminal decompression, and better preservation of the facet joint, making it a valuable and comparable alternative with additional perioperative benefits for managing pathologies in the L5/S1 region with a high iliac crest.</p>