Nerve root decompression with instrumented fusion is currently most commonly performed in the treatment of patients with spondylolytic spondylolisthesis. The relationship between successful fusion and clinical outcome remains controversial, thereby questioning the necessity of fusion. Nerve root decompression without fusion, i.e. Gill's procedure, might be a less invasive surgical alternative with comparable clinical outcome. The objective of this study is to compare the long-term results of Gills's procedure with data from literature on decompression with fusion, and, moreover, to determine if a future randomised trial is legitimate. We retrospectively reviewed the long-term results of Gill's procedure in patients with grade I or II spondylolytic spondylolisthesis. All patients suffered from leg pain with or without low back pain. No patient had low back pain alone. In 17 patients a bilateral and in 25 patients a unilateral Gill's procedures were performed. The patients were evaluated at three follow-up moments. On moment 1, 38 patients were clinically examined on their last out-patient control (mean follow-up 11 months). On moment 2, 34 patients were interviewed by telephone (mean follow-up 4.4 years). The final long-term follow-up moment 3 (mean follow-up 10.5 years) included a mailed patient-satisfaction questionnaire of 31 patients (response rate 74%). No surgical complication occurred. Ten of the 42 patients were reoperated because of persistent or recurrent radicular pain (mean time interval 2.9 years). Kaplan-Meier analysis showed a disease-free survival rate of 79% at 5 years and 72% at 10 years after the index operation. On the three follow-up moments, the improvement of leg pain was 92, 97 and 88%, respectively. The final long-term follow-up showed 71% good result in terms of patient satisfaction. The Gill's procedure is a less invasive surgical technique in the treatment of patients with leg pain due to low-grade spondylolytic spondylolisthesis. This technique can be considered as an alternative to instrumented fusion in selected cases. Preoperative instability, discectomy at the affected level and neuroforaminal nerve root compression seem to be negative influencing factors, increasing the risk for secondary instrumented surgery. The results of this study justify a randomised trial.