Indocyanine green (ICG) can be used to measure cardiac output (CO), hepatic function, and blood volume. We used ICG to describe the effect of right hepatectomy for living liver donation on intraoperative hemodynamics and perioperative liver function. ICG disposition was determined in 12 healthy adult living liver donors during the dissection phase and immediately after removal of the right hepatic lobe. In addition, measurements were repeated postoperative day 5. After injecting ICG, plasma concentrations were obtained for approximately 10 minutes by noninvasive pulse dye densitometry. CO was significantly higher and systemic vascular resistance was significantly lower immediately after removal of the right lobe compared with those obtained before resection (6.02 +/- 1.12 v 10.28 +/- 3.84 L/min; P < .05; 639 +/- 254 v 1,007 +/- 264 dyn x s x cm(-5); P < .05). Heart rate also increased significantly after removal of the right lobe from 62 +/- 10 to 83 +/- 9 beats/min (P < .05). Mean arterial pressure and central venous pressure were not different between measurements. The average elimination rate constant of ICG (K(ICG)) was reduced by more than 50% immediately after resection of the right lobe in comparison to baseline (0.25 +/- 0.096 v 0.12 +/- 0.03; P < .05). Day 5, K(ICG) was still decreased from baseline (0.25 +/- 0.096 v 0.16 +/- 0.04; P < .05), but approximately 25% greater than the immediate postresection K(ICG) (0.16 +/- 0.04 v 0.12 +/- 0.03; P > .05). Findings show profound intraoperative hemodynamic changes during living liver donation. In addition, we show that functional recovery of the liver is likely to be slower than morphological recovery, and such clinical parameters as coagulation profile may not be a good index of fully restored hepatic function.