In vitro blood/air partition coefficients (KB/A) for acetone, 1,1,1-trichloroethane, toluene, and styrene were measured in blood samples from 73 human subjects and correlated with blood chemistry parameters (hematocrit, total cholesterol, serum triglycerides, serum albumin, total plasma proteins, Na+, K+, Cl-, and HCO3-). Statistically significant inter-individual variation existed in KB/A between some subjects. Substitution of group or generic in vitro KB/A values for values determined in some individuals could introduce errors of up to 50%. However, most subjects could be well represented by group averages (mean +/- SD; acetone, 301 +/- 22; 1,1,1-trichloroethane, 6.0 +/- 0.8; toluene, 19 +/- 3; styrene, 62 +/- 10). The KB/A values for acetone, 1,1,1-trichloroethane and toluene were normally distributed. The data for styrene appeared to deviate from a normal distribution and may have been bimodal. The KB/A values for the two structurally related compounds, toluene and styrene, were strongly correlated within individuals, while the KB/A values for compounds with less structural similarity, such as acetone and styrene, were poorly correlated. At most, 15% of the variation in KB/A among individuals could be explained by variation in the measured blood chemistry parameters. When the entire sample group was considered, blood chemistry parameters were not significantly correlated with KB/A for any compound. The KB/A of 1,1,1-trichloroethane was significantly correlated with the concentration of cholesterol and triglycerides in females. Sex was a significant grouping variable for the correlation of albumin concentration with the KB/A of styrene. Age was not a significant correlation variable. Blood chemistry parameters which previously have been correlated with KB/A in small sample groups do not appear to be significantly correlated in our larger sample group.