OBJECTIVE: Determine if increased intra-abdominal pressure (IAP) alone can cause systemic hypertension in a chronic canine model. DESIGN: Evaluate effects of increase in IAP with progressive in¯ation and de¯ation of an intra-abdominal balloon on systemic blood pressure in experimental and control animals. SUBJECTS: Male dogs weighing 15 ± 25 kg underwent placement of an intra-abdominal balloon which was progressively in¯ated on a weekly basis in the experimental animals (5) over 4 weeks to 25 mmHg above baseline and kept there for an additional 2 weeks before gradual de¯ation over 2 weeks. Control animals (5) had the balloon placed but not in¯ated. Pain was controlled with osmotic analgesic pumps. MEASUREMENTS: The animals were anesthetized, blood pressure (BP) measured and blood drawn for plasma renin activity (PRA), aldosterone, atrial naturetic peptide (ANP), catecholamines, and serum sodium (Na). A right heart catheter was inserted for measuring cardiac output (CO) and pulmonary artery occlusion pressure (PAOP) at baseline, week 5 (maximal IAP) and week 7 (after balloon de¯ation). The animals were weighed and urinary bladder pressures recorded weekly before and after abdominal balloon in¯ation. RESULTS: Systolic (122 AE 3 to 155 AE 5 mmHg, P`0.05) and diastolic (82 AE 4 mmHg to 107 AE 7 mmHg, P`0.05) BP rose at 5 weeks at 25 mmHg IAP b baseline and returned to control with balloon de¯ation. Both systolic and diastolic BP rose (P`0.05) above control animals BP at 15 mmHg IAP at 2 weeks and remained elevated until abdominal decompression, at week 7. There were no signi®cant changes in net animal weight, PRA, aldosterone, ANF, catecholamines, Na, CO or PAOP. CONCLUSION: Increased IAP from progressively in¯ating an intra-abdominal balloon in dogs was associated with signi®cant increases in systolic and diastolic BP that resolved with balloon de¯ation. Increased IAP may be a cause for systemic hypertension in central obesity and pre-eclampsia.