The implantable gastric stimulator (IGS), a pacemaker-like device, has been found to be safe and effective to induce and maintain weight loss. We present our experience with 20 morbidly obese patients. Between September 20 and November 22, 2002, 20 patients (F/M 12/8), mean age 40.3 years (23-62) underwent IGS implantation. Mean BMI was 40.9 (33.9-48.2), mean weight 115.0 kg (87.0-137.0) and mean excess weight (EW) 51.3 kg (35.6-70.1).Co-morbitidies were: 3 cases of hypertension, 1 diabetes, 1 dislipidemia and 1 depression. Mean operative time was 58.5 min (37-85). The IGS was actived 30 days after implantation. Patients were advised to follow a low calorie diet and behavior modification (to avoid fat and to ingest more liquids during meals, to chew slowly, to eat vegetables before main meals, and to perform exercise daily). Mean +/- standard error percent excess weight loss (%EWL) was: 10.6+/-1.8 at 1 month; 15.0+/-2.3 at 2 months; 16.6+/-2.6 at 3 months; 18.1+/-3.5 at 4 months; 15.5+/-3.5 at 6 months; 18.9+/-3.5 at 8 months; and 23.8+/-5.0 at 10 months. There were no intra-operative surgical or long-term complications. There were 3 intra-operative gastric penetrations, observed by gastroscopy, without sequelae. One patient with hypertension ceased his medical therapy at the 4th month. IGS can be implanted laparoscopically with minimal perioperative complications. The observed weight loss is comparable to other noninvasive procedures. If weight loss is maintained, IGS could be considered as a first choice therapy in the treatment of morbid obesity in selected patients.