Background The intragastric balloon, filled with air or liquid is used before elective bariatric surgery because its efficacy is limited. This might be the consequence of altered gastric functions. Therefore, we aimed to investigate, in an animal model, the changes in gastric motility and emptying induced by long-term insertion of a balloon used for weight reduction. Methods Ten Gottingen mini-pigs were allocated into two groups with and without an intragastric balloon for 5 months. Balloons were inserted under endoscopy during general anesthesia and were filled with 350 mL of air. Gastric emptying was evaluated by scintigraphy. Gastric volume was measured by single photon emission computed tomography and proximal gastric compliance obtained using an electronic barostat. Changes in vagal tone were assessed by heart rate variability (HRV). Key Results After balloon insertion, gastric volume was significantly increased (2047 +/- 114.8 cm3 after vs 1674 +/- 142.5 cm3 before insertion, P < 0.05). Gastric compliance was also larger in balloon group (219 +/- 23.4 mL mmHg-1 in balloon vs 168 +/- 7.7 mL mmHg-1 in control group). Gastric emptying was reduced after insertion of the balloon (T(1/2) = 204 +/- 28.8 min vs 159 +/- 25.4 before vs after insertion). High frequency components of the spectral analysis of HRV, representing vagal tone, were increased in balloon group. Conclusions & Inferences The proximal stomach was enlarged after the insertion of a balloon in the stomach as a consequence of an increased gastric compliance. This change in compliance was probably causative for a reduction in gastric emptying rate of solids. These alterations were associated with increased vagal tone.