ABSTRACT Background The unique positioning of the patient at steep Trendelenburg with prolonged and increased intra-abdominal pressure (IAP) during robotic radical prostatectomy may increase the risk of splanchnic ischemia. We aimed to investigate the acute effects of IAP and steep Trendelenburg position on the level of ischemia modified albumin (IMA) and to test if serum IMA levels might be used as a surrogate marker for possible covert ischemia during robotic radical prostatectomies. Patients and Methods Fifty ASA I-II patients scheduled for elective robotic radical prostatectomy were included in this investigation. Exclusion criteria The patients were excluded from the study when an arterial cannulation could not be accomplished, if the case had to be converted to open surgery or if the calculated intraoperative bleeding exceeded 300ml. All the patients were placed in steep (45 degrees) Trendelenburg position following trocar placement. Throughout the operation the IAP was maintained between 11-14mmHg. Mean arterial blood pressure (MAP), cardiac output (CO) were continuously monitored before the induction and throughout the surgery. Blood gases, electrolytes, urea, creatinine, alanine transferase (ALT), aspartate transferase (AST) were recorded. Additionally, IMA levels were measured before, during and after surgery. Results (1) MAP, CO, lactate and hemoglobin (Hb) did not significantly change in any period of surgery (p>0.05); (2) sodium (p<0.01), potassium (p<0.05) and urea (p<0.05) levels decreased at postoperative period, and no significant changes at creatinine, AST, ALT levels were observed in these patients; (3) At the end of surgery (180 min) pCO2, pO2, HCO3 and BE did not change compared to after induction values (p>0.05) but mild acidosis was present in these patients (p<0.01 vs. after induction); (4) IMA levels were found to be comparable before induction (0.34±0.04), after induction (0.31±0.06) ...