Study Objective: To evaluate the effects of an intravenous infusion of prostaglandin E1 (PGE1) on hepatic blood flow.Design: Prospective clinical study.Setting: University-affiliated hospital.Patients: 16 ASA physical status I and II surgical patients who were scheduled for abdominal surgery.Interventions: Patients were anesthetized with 1% sevoflurane and 66% nitrous oxide. PGE1 0.05 mg/kg/min or PGE1 0.10 mg/kg/min was continuously infused, followed by an infusion of 1000 mL Ringer's acetate solution.Measurements: The hemodynamic effect of PGE1 was examined using pulse dye densitometry (PDD). A nose probe for PDD was used, and 10 mg indocyanine green (ICG) in 2 mL distilled water was bolus-infused into a central venous catheter for each measurement. Cardiac output (CO), circulating blood volume (CBV), and plasma dye clearance rate (K) were monitored from the dye-densitogram. Hepatic blood flow was estimated using the K and CBV values.Main Results: PGE1 did not increase CBV or CO. Even adding a 1000 mL crystalloid infusion did not expand CBV, whereas mean arterial pressure (MAP) significantly decreased from 91.1 +/- 16.5 mmHg to 84.8 +/- 13.5 mmHg (PGE1 0.05 μg/kg/min) and 80.6 +/- 14.4 mmHg (PGE1 0.10 μg/kg/min ) (p < 0.01 compared with control value), then to 72.0 +/- 6.5 mmHg (PGE1 0.10 μg/kg/min + 1000 mL Ringer's acetate) (p < 0.01 compared with control value). Hepatic blood flow changes were 1.46 +/- 0.60 L/min (control), 1.48 +/- 0.45 L/min (PGE1 0.05 μg/kg/min), 1.14 +/- 0.35 L/min (PGE1 0.10 μg/kg/min), and 1.15 +/- 0.19 L/min (PGE1 0.10 μg/kg/min + 1000 mL Ringer's acetate) (no significant difference, p < 0.05). Hepatic blood flow and K values did not statistically significantly differ at each condition.Conclusions: PGE1 does not affect blood volume shift, CO, or hepatic blood flow.