Intra-abdominal pressure (IAP), measured via a transurethral catheter, hemodynamic, and renal functions were evaluated in 25 cirrhotic patients admitted to ICU with variceal bleeding, tense ascites, and peripheral edema. In patients with an IAP greater than 25 cm H2O, a paracentesis was performed to decrease the IAP by 10 cm H2O. After paracentesis, a decrease in the IAP from 33.47 to 19.06 cm H2O (p less than 0.001) resulted in a decrease in total peripheral resistance (TPR) (p less than 0.01) and a significant increase in cardiac index (CI) (p less than 0.001), stroke index (p less than 0.001), left ventricular stroke work (LVSW) (p less than 0.01), and right ventricular stroke work (p less than 0.01). The therapeutic effects of paracentesis on renal function were: a decrease in BUN and serum creatinine (p less than 0.001) and an increase in the creatinine clearance (Ccr) (p less than 0.001), urine volume (p less than 0.001), osmolar clearance (Cosm) (p less than 0.001), and urine creatinine (p less than 0.001) values. The IAP correlated directly with the TPR (r = +0.35, p less than 0.01) and inversely with the CI (r = -0.39, p less than 0.001) and LVSW (r = -0.37, p less than 0.001) in the 126 studies of IAP performed with the 25 patients. IAP also correlated directly with BUN (r = 0.40, p less than 0.001), serum creatinine (r = 0.28, p less than 0.01), and free water clearance (CH2O) (r = 0.3, p less than 0.001); IAP correlated negatively with Ccr (r = -0.54, p less than 0.001) and Cosm (r = -0.43, p less than 0.001). In critically ill cirrhotic patients, IAP, when measured noninvasively via a bladder catheter, is an accurate and useful method to follow manipulation of ascitic fluid pressure quantitatively in order to optimize hemodynamic and renal function.