Background Ghrelin has been shown to stimulate gastric emptying in healthy humans and patients with delayed gastric emptying. The aim of this study is to assess the effect of ghrelin on gastric emptying on day 2 after open colorectal surgery. Methods Twenty-four patients (mean age 69.2 +/- 1.4, BMI 25.8 +/- 0.8kgm2) were randomized to saline or ghrelin infusion (15pmolkg1min1) during 3h before and on day 2 after open colorectal surgery. Of these, 20 were assessed both before and after surgery. At start of infusion, a liquid meal (480kcal, 200mL) was administered together with 1.5g acetaminophen. Plasma was obtained at regular intervals together with visual analogue scales for hunger, satiety and nausea. Acetaminophen was analyzed as a marker of gastric emptying. Plasma glucose, insulin, acyl-ghrelin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinoptrophic peptide (GIP), pancreatic polypeptide and peptide YY (PYY) were analyzed. Key Results Gastric emptying was faster during ghrelin infusion compared to saline before and after surgery (P<0.02). In addition, plasma glucose was increased (P<0.05). With ghrelin infusion, plasma insulin was unchanged except for lower values postoperatively (P<0.05). Ghrelin did not alter plasma concentrations of gut peptides. After surgery, ghrelin shortened the time to first bowel movement compared to saline (2.1 +/- 0.3 vs 3.5 +/- 0.4days, P=0.02). Conclusions & Inferences A 3-h ghrelin infusion increased the gastric emptying rate and hastened the time to first bowel movement after surgery. Ghrelin/ghrelin receptor agonists have a therapeutic potential in postoperative ileus; Karolinska Clinical Trial Registry nr CT20110084.