Objective: To examine factors influencing conversion from a laparoscopic to an open procedure in patients requiring surgery for Crohn's disease. Summary Background Data: Laparoscopic management of patients with complications of Crohn's produces better outcomes than traditional open approaches, but it is difficult to determine before surgery who will be amenable to laparoscopic management. In this series, a laparoscopic approach was offered to virtually all patients to determine reasons for laparoscopic failure. Methods: Data regarding patients who underwent attempted laparoscopic procedures for Crohn's (January 1993 to June 2000) were collected prospectively. The bowel was mobilized laparoscopically and extracorporeal anastomoses were performed. Conversion to open surgery was defined as creation of an incision of more than 5 cm. Results: One hundred ten patients (age 37 ± 1.1 years, 58% female) underwent 113 attempted laparoscopic interventions. Indications for surgery included obstruction (77%), failure of medical management (35%), fistula (27%), and perineal sepsis (4%). Sixty-eight procedures (60%) were completed laparoscopically. Procedures completed laparoscopically included ileocecectomy (n = 46), small bowel resection (n = 22), fecal diversion (n = 7), intestinal stricturoplasty (n = 7), resection of prior ileocolonic anastomosis (n = 5), segmental colectomy (n = 1), and lysis of adhesions (n = 1). Forty-five procedures (40%) were converted as a result of adhesions (n = 21), extent of inflammation or disease (n = 9), size of the inflammatory mass (n = 7), inability to dissect a fistula (n = 5), or inability to assess anatomy (n = 3). Factors associated with conversion were internal fistula as an indication for surgery, smoking, steroid administration, extracecal colonic disease, and preoperative malnutrition. In laparoscopic patients, mean times to passage of flatus and first bowel movement were 3.6 ± 0.2 days and 4.4 ± 0.2 days, respectively. Mean time to discharge was 6 ± 0.2 days. Conclusions: Attempted laparoscopic management is safe and effective if there is an appropriate threshold for conversion to an open procedure. Conversion factors identified in this study largely reflect technical challenge and severity of disease. Patients taking steroids and those with known fistulas or colonic involvement threaten laparoscopic failure, but many of these patients can be managed laparoscopically and have better outcomes. By understanding the reasons for conversion, it is hoped that the chances of laparoscopic success can be improved by modifying standard preoperative medical management or using additional technological capabilities (e.g., robotics).