77 patients with lumbar disc herniation between L3-5 and scheduled for discectomy were randomized to surgery with or without the addition of an interspinous spacer (Wallis dynamic stabilization system; Zimmer). Patients were assessed for clinical and radiographic outcome after 3 years. At 3 years, no significant differences between groups were noted in pain scores on a visual analog scale, the Japanese Orthopaedic Association score, or the Oswestry Disability Index (ODI). Disc height at 3 years was significantly greater in the interspinous spacer group, however. There was no significant difference between groups in the incidence of complications.