Background: Adhesive small bowel obstruction (ASBO) is an important cause of hospital admission, is associated with significant morbidity and mortality, and therefore is a substantial burden for healthcare systems worldwide. Icodextrin 4% solution (Adept, Shire Pharmaceuticals, UK) is a high-molecular-weight a-1,4 glucose polymer approved in Europe for use as intraoperative lavage and postoperative instillation to reduce the occurrence of post-surgery intra-abdominal adhesions. The present clinical study aimed to evaluate the safety and effectiveness of icodextrin 4% in decreasing the incidence, extent, and severity of adhesions in patients after abdominal surgery for ASBO. Methods: The study was a single-center prospective, randomized investigation. The study is designed and conducted in compliance with the principles of Good Clinical Practice regulations. Safety and efficacy of icodextrin 4% in the study group are compared to no anti-adhesion treatment in a parallel control group with blinded evaluation of primary endpoints. Primary endpoints are the evaluation of the therapeutic role of icodextrin 4% in reducing ASBO recurrence incidence and the need of laparotomies for ASBO recurrence, as well as adhesion formation (with evaluation of their incidence, extent, and severity). A sum of 181 patients with ASBO and surgical indication to laparotomy were enrolled and randomized in two groups. Patients were submitted to adhesiolysis with bowel resection if required with or without anastomosis. The first group received traditional treatment (control group), whereas the second group was treated with the addition of icodextrin 4% solution before the abdominal closure. Results: Ninety-one patients were randomized to have icodextrin 4% solution administered intraperitoneally, and 90 patients were randomized to have the traditional treatment. The two study groups were homogeneous regarding their baseline characteristics. The ASBO recurrence rate was 2.19% (2/91) in the icodextrin groups vs 11.11% (10/90) in the control group after a mean follow-up period of 41.4 months (p < 0.05). No differences were found in the need of laparotomies for ASBO recurrence in the studied groups. The adhesion severity score seems lower in the group treated with the addition of icodextrin (p = n.s.). Conclusions: The data resulting from this RCT showed that the use of icodextrin 4% solution in ASBO is safe and reduces intra-abdominal adhesion formation and the risk of re-obstruction. © 2011 The Society for Surgery of the Alimentary Tract.