Intra-abdominal surgical intervention can cause the development of intra-peritoneal adhesions. To reduce this problem, different agents have been tested to minimize abdominal adhesions; however, the optimal adhesion prophylaxis has not been found so far. Therefore, the A-Part(®) Gel was developed as a barrier to diminish postsurgical adhesions; the aim of this randomized controlled study was a first evaluation of its safety and efficacy. In this prospective, controlled, randomized, patient-blinded, monocenter phase I-II study, 62 patients received either the hydrogel A-Part-Gel(®) as an anti-adhesive barrier or were untreated after primary elective median laparotomy. Primary endpoint was the occurrence of peritonitis and/or wound healing impairment 28 ± 10 days postoperatively. As secondary endpoints anastomotic leakage until 28 days after surgery, adverse events and adhesions were assessed until 3 months postoperatively. A lower rate of wound healing impairment and/or peritonitis was observed in the A-Part Gel(®) group compared to the control group: (6.5 vs. 13.8 %). The difference between the two groups was -7.3%, 90 % confidence interval -20.1, 5.4 %. Both treatment groups showed similar frequency of anastomotic leakage but incidence of adverse events and serious adverse events were slightly lower in the A-Part Gel(®) group compared to the control. Adhesion rates were comparable in both groups. A-Part Gel(®) is safe as an adhesion prophylaxis after abdominal wall surgery but no reduction of postoperative peritoneal adhesion could be found in comparison to the control group. This may at least in part be due to the small sample size as well as to the incomplete coverage of the incision due to the used application. NCT00646412.