Objective:To investigate the short term clinical efficacy of intra-gastric balloon (IGB) on obesity patients with different body mass index (BMI).Methods:The retrospective and descriptive study was conducted. The clinical data of 62 obesity patients with different BMI who were admitted to three medical centers, including 56 cases in the Hurstville Private Hospital, 4 cases in the St George Private Hospital of University of New South Wales and 2 cases in the East Sydney Private Hospital, from January 2017 to December 2021 were collected. There were 15 males and 47 females, aged 45.1(range, 18.0 to 67.0)years, with the BMI of 35.1(range, 27.8 to 48.4)kg/m 2. Of the 62 patients, there were 33 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 29 cases with BMI≥35 kg/m 2. Observation indicators: (1) first operation and postoperative complications; (2) follow-up after first IGB; (3) recurrent IGB and postoperative complications; (4) follow up after recurrent IGB. Follow-up was conducted using outpatient examinations to detect postoperative complications and weight loss effects. Patients were followed up at postoperative 1, 3, 6 month. Measurement data with normal distribution were represented as Mean± SD, and measurement data with skewed distribution were represented as M (range). Count data were described as absolute numbers. Results:(1) First opera-tion and postoperative complications. All 62 obesity patients underwent the first IGB successfully. Of the 62 patients, 45 cases had postoperative complications, including 38 cases with gastroesophageal reflux, 12 cases with dysphagia or burping, 9 cases with epigastric pain and 4 cases with nausea. One patient may have multiple complications. Cases with above complications in the 33 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 29 cases with BMI≥35 kg/m 2 were 21, 8, 7, 2 and 17, 4, 2, 2, respectively. (2) Follow-up after first IGB. Of the 62 obesity patients, there were 52, 46 and 38 cases completing followed up at postoperative 1, 3 and 6 month, respectively, including 30, 25,20 cases in patients with 27 kg/m 2≤BMI<35 kg/m 2 and 22, 21, 18 cases in patients with BMI≥35 kg/m 2. Of the 62 obesity patients, there were 15 cases requiring early balloon extraction due to intractable symptoms, inclu-ding 7 cases with ongoing dysphagia or burping, 6 cases with complaining of ineffective weight loss, 1 case with acute right-sided abdominal pain and 1 case with a serendipitous discovery of pregnant. The cumulative weight loss of the 30 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 22 cases with BMI≥35 kg/m 2 at postoperative 1 month was (4.8±3.0)kg and (6.6±2.8)kg, respectively. The above indicator was (6.7±4.4)kg and (10.6±4.8)kg at postoperative 3 month for the 25 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 21 cases with BMI≥35 kg/m 2, and (8.5±4.8)kg and (9.8±3.9)kg at postoperative 6 month for the 20 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 18 cases with BMI≥35 kg/m 2. The percentage of excess weight loss was 53%±26% and 29%±15% at postoperative 6 month and the percentage of total weight loss was 14%±5% and 10%±5% at postoperative 6 month for the 20 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 18 cases with BMI≥35 kg/m 2, respectively. (3) Recurrent IGB and postoperative complications. Of the 38 cases completing the postoperative 6 month followed up after the first IGB, 9 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 7 cases with BMI≥35 kg/m 2 choosing a second IGB immediately after the removal of the first balloon. Cases with postoperative compli-cations, including gastroesophageal reflux, dysphagia or burping, epigastric pain, nausea were 4, 3, 0, 0 in patients with 27 kg/m 2≤BMI<35 kg/m 2 and 4, 0, 2, 1 in patients with BMI≥35 kg/m 2. (4) Follow up after recurrent IGB. All the 16 patients who chosen a second IGB completed the postoperative 6 month followed up, with the cumulative weight loss of (8.8±8.5)kg and (18.9±9.7)kg and the percentage of excess weight loss of 44%±38% and 41%±15% in the 9 cases with 27 kg/m 2≤BMI<35 kg/m 2 and 7 cases with BMI≥35 kg/m 2, respectively. Conclusions:IGB can achieve a good short-term weight loss effects in obesity patients with BMI≥27 kg/m 2. Gastroesophageal reflux, dysphagia or burping, epigastric pain and nausea are common postoperative complications.