Background : Drainage of ascitic fluid is a common practice in order to relief the respiratory discomfort of patients. Aim: To determine the relation between the intra-abdominal pressure (IAP) and extracted volume of the ascitic fluid, in order to calculate abdominal compliance (Cabd). Settings and Design : A study was designed at AHEPA University Hospital and analysed with prospectively collected data. Materials and Methods : Fifteen patients with tension ascites that had transcutaneous drainage with a wide catheter. The ascitic fluid removed was measured, while the IAP and a Visual Analogue Scale (VAS) score for dyspnea were recorded before and 15 min after the puncture. Cabd was calculated. Statistical Analysis : The data were analysed with descriptive statistics, paired Student's t-test and Pearson coefficiency. Results : The predrainage IAP was 18.26 mmHg (SD 1.67 mmHg), while the postdrainage was 14.46 mmHg (SD 1.34 mmHg) (P