Colonoscopy results are not enhanced by use of magnet endoguide in specialist practice. INTRODUCTION: It is discussed whether the use of a magnetic positioning device (OLYMPUS; UPD (unit of magnetic positioning device)) enhances the success of the colonoscopic procedure. Concern for patient compliance and endoscopic efficiency has been voiced in connection with the implementation of colon cancer screening. UPD has been proposed as a tool for optimization of results and reduction of patient discomfort. In this study, we aimed to qualify the debate by examining the success rate and patient discomfort in an unselected colonoscopy population referred to specialist clinics with experienced investigators. Furthermore, the study assessed the effect of using a UPD. MATERIAL AND METHODS: A total of 1,068 consecutive patients referred for colonoscopy were enrolled and randomised for investigation with or without use of UPD. The evaluation endpoints were: success rate (coecum visualised, ileal intubation was carried out at the investigator's discretion), duration of procedure, and patient discomfort indicated by the patient as a visual analogue scale score. RESULTS: No significant differences between the two investigational procedures were demonstrated in relation to the chosen endpoints. CONCLUSION: UPD is convenient to have, but not a necessity for colonoscopy. FUNDING: The study was supported by the Danish Association of Medical Specialists. TRIAL REGISTRATION: The study was approved by the Danish Data Protection Agency, journal no. 2009-41-3716, the National Ethics Committee, journal no.: H-1-2009-80, and registered with ClinicalTrials.gov., protocol no: NCT01055782.