A number of interspinous process devices have recently been introduced to the lumbar spinal market as an alternative to conventional surgical procedures in the treatment of symptomatic lumbar stenosis. One of those "dynamic" devices is the Coflex device which has been already implanted worldwide more than 14,000 times. The aim of implanting this interspinous device is to unload the facet joints, restore foraminal height and provide stability in order to improve the clinical outcome of surgery. Published information is limited, and there are so far no data of comparison between the implant and traditional surgical approaches such as laminotomy. The purpose of our prospective study is to evaluate the surgical outcome of decompressive surgery in comparison to decompressive surgery and additional implantation of the Coflex interspinous Device. 60 patients who were all treated in the Spine Center of Klinikum Neustadt, Germany for a one or two level symptomatic LSS with decompressive surgery were included. Two groups were built. In Group one (UD) we treated 30 patients with decompression surgery alone and group two (CO) in 30 patients a Coflex device was additional implanted. Pre- and postoperatively disability and pain scores were measured using the Oswestry disability index (ODI), the Roland-Morris score (RMS), the visual analogue scale (VAS) and the pain-free walking distance (WD). Patients underwent postoperative assessments 3, 6 and 12 month including the above-mentioned scores as well as patient satisfaction. In both groups we could see a significant improve (p < 0.001) in the clinical outcome assessed in the ODI, in the RMS for evaluation of back pain, in the VAS and in the pain-free WD at all times of reinvestigation compared to base line. At 1-year follow up there were no statistically differences between both groups in all ascertained parameters including patient satisfaction and subjective operation decision. Because there is no current evidence of the efficacy of the Coflex device we need further data from randomized controlled studies for defining the indications for theses procedures. To the best of our knowledge this is the first prospective controlled study which compares surgical decompression of lumbar spinal stenosis with additional implanting of an interspinous Coflex device in the treatment of symptomatic LSS.