Objective: To determine and compare the effects of hematocrit and serum constituents on the blood solubilities of volatile anesthetics in different cardiac surgical patients. Design: Descriptive Setting: University hospital. Participants: Twenty healthy adult volunteers, 40 adult cardiac patients, and 20 pediatric cardiac patients. Measurements and Main Results: Blood/gas partition coefficients of desflurane, isoflurane, and halothane; hematocrit; and serum concentrations of cholesterol, triglyceride, albumin, and globulin were determined in healthy adult volunteers, adult patients with coronary artery disease or rheumatic heart disease, and pediatric patients with cyanotic or acyanotic congenital heart disease. Statistical analysis was used to determine the difference in serum constituents and blood solubility of each anesthetic among volunteers and patients with different cardiac diseases. Triglyceride and blood/gas partition coefficients of the 3 volatile anesthetics in the patients with coronary artery disease were significantly higher than those in healthy volunteers and the patients with rheumatic heart disease (p < 0.05). Hematocrits were significantly higher in cyanotic children than acyanotic children (p < 0.05), but the serum constituents and anesthetic solubilities were not different between the 2 groups (p > 0.05). Conclusion: Patients with coronary artery disease have significantly higher serum triglyceride and blood/gas partition coefficients for desflurane, isoflurane, and halothane than healthy volunteers and patients with rheumatic heart disease. Although cyanotic children have higher hematocrits compared with acyanotic children, no significant difference in anesthetic blood gas solubilities was found between the 2 groups. Copyright (C) 2001 by WB. Saunders Company.