The oxygen transport capacity of fluorocarbons was investigated in the hamster chamber window model microcirculation to determine the rate at which oxygen is delivered to the tissue in conditions of extreme hemodilution (hematocrit, Hct 11%) using hydroxyethly starch (HES, 200 kDa MW) as a plasma expander attained by 2 isovolemic hemodilutions performed with 10% HES until Hct was 65%. A third step reduced Hct to 75% of baseline and was performed with either HES or a 60% perfluorocarbon (PFC) emulsion. Comparisons of HES only hemodiluted animals vs. 4.2 g/kg PFC emulsion hemodiluted animals were made at 21 and 100% normobaric oxygen ventilation. It was found that systemic and microcirculation oxygen delivery was 25% and 400% higher in the PFC animals as compared to HES animals, respectively, showing that PFCs deliver oxygen to the tissue when combined with hyperoxic ventilation in the present experiments, with no evidence of vasoconstriction or impaired microvascular function. 100% oxygen ventilation led to a positive base excess for the PFC group (5.5±2.5 mmol/l) vs. a negative balance (−0.8 ± 1.4 mmol/l) for the HES group, suggesting that microvascular findings corresponded to systemic events.