SUMMARY -Th e purpose of the study was to point to the importance of measuring intra-abdominal pressure (IAP) and of early recognition of the consequences of increased IAP on basic vital functions. Measurement of IAP via urinary bladder was conducted every 12 hours in 70 surgical patients with acute abdominal syndromes not previously operated on. Based on the measured IAP values, all patients were divided into groups of patients with normal IAP values (n=20) and patients with increased IAP values (n=50) . Vital functions and basic laboratory analysis were monitored and the values obtained were compared with IAP in both patient groups. A statistically signifi cant diff erence was found in body weight, body mass index, urine output, creatinine, urea, heart rate, partial pressure of oxygen (PaO 2 ) and partial pressure of carbon dioxide (PaCO 2 ) between patients with normal and increased IAP values. Th e increase in IAP values was found to be associated with an increase in PaCO 2 , respiratory rate, peak inspiratory pressure, central venous pressure, heart rate, Acute Physiology, Age and Chronic Health Evaluation II score, mortality rate, creatinine and urea values, and number of days of treatment in the intensive care unit. At the same time, the values of PaO 2, blood oxygen saturation, diuresis and abdominal perfusion pressure were declining. IAP measurement is an old, cost-eff ective, reliable technique that is easy to perform and should be applied in all high risk patients.