Aim: Postoperative ileus is an important factor of complications following gastrointestinal procedures. Its pathophysiology and the parameters, which may impact on its duration, remain unclear. The aim of this study was to measure the role of various clinical determinants on restoration of intestinal function after elective colorectal surgery. Methods: From July 2002 to September 2003, all patients who underwent laparotomy for colectomy (laparoscopic resections excluded) with either an ileotransverse, colocolic, or high colorectal anastomosis were entered in this prospective study. The intervals in hours between the end of the surgical procedure and passing of flatus (PG) and passing of stool (PS) were recorded by an independent investigator. PG and PS were eventually correlated with the following parameters: type of colectomy, early removal of nasogastric tube (NGT), mechanical bowel preparation (MBP), type of underlying disease, systemic administration of opiates, and surgical training (colorectal fellowship or other). Results: One hundred twenty-four patients were entered in this study. Four patients (3.2%) developed septic complications (3 anastomotic leaks and 1 intraabdominal abscess) and were excluded from the analysis. Median age in this population was 68 (range 30–95) years. Mean duration of postoperative ileus was 70±28 h (PG) and 99±34 h (PS). The type of colectomy, underlying disease, MBP, and early NGT removal failed, in univariate analysis, to correlate with the duration of postoperative ileus. By contrast, time intervals PG and PS were statistically shorter in the group of patients treated by a colorectal surgeon [56±23 vs 74±28 h (PG); 82±26 vs 103±35 h (PS), p=0.004], as well as in patients who received systemic opiates for less than 2 days [64±27 vs 75±28 h (PG), p=0.04; 88±32 vs 108±33 h (PS), p=001]. Conclusion: Restoration of normal intestinal function after elective open colectomy takes 3 (PG) to 4 (PS) days. In our series, specialized training in colorectal surgery has a positive impact on the duration of postoperative ileus. Surgical specialization should be considered an important parameter in future clinical trials aiming to minimize postoperative ileus.