Hypothesis: We hypothesized that hand-assisted laparoscopic surgery (a new technique that involves a surgeon's hand passing through a pneumoperitoneum-protecting sleeve device and assisting in laparoscopic surgery) is leasable and outcomes are comparable to purely laparoscopic procedures in selected cases. Design: A prospective, multicenter, nonrandomized, noncontrolled study was conducted with the participation of expert laparoscopic surgeons. Setting: Academic and community medical centers in 16 states. Patients: Any patient 18 years or older requiring abdominal surgery and determined to be suitable for laparoscopic surgery. Main Outcome Measures: Incision size, duration of the procedure, conversion rate to an open technique, detection of subtle disease, return of bowel function, length of hospital stay, complication rate, and subjective evaluation. Results: The device was used in 58 patients for 24 different procedures, most commonly during colectomy (n = 21) and splenectomy (n = 7). Twenty-two percent of cases required conversion to open technique because of failure to maintain pneumoperitoneum or failure to complete the anticipated operation by this method. Average incision size was 7.6 cm. Mean duration of all procedures was 223 minutes (range, 110-415 minutes) and for nonconverted procedures was 178 minutes (range, 65-540 minutes). Preoperatively undetectable, subtle disease was palpated in 14 patients (24%). Mean length of hospital stay for all patients was 7.9 days and for the nonconverted group was 6.7 days. Twenty- four percent of patients developed complications, most commonly either wound complications (n = 4) or prolonged ileus (n = 3). In 58% of cases, surgeons thought that the technique shortened surgery, and 88% of surgeons found the technique 'helpful' in all the completed procedures. Conclusions: This technique seems to be a useful tool in the management of cases that either are too complex or take too long to be managed with purely minimally invasive techniques. To further define the potential benefits of this technique in selected procedures, prospective randomized trials are needed.