Henry's law constants of tetrachloroethylene, trichloroethylene, cis-dichloroethylene, and trans-dichloroethylene in air-aqueous surfactant systems were experimentally determined by the equilibrium partitioning in closed systems method. Polyoxyethylene (10) octylphenol, sodium dodecyl sulfate, and cetyltrimethylammonium bromide were used as surfactants. The effects of temperature and surfactant concentration were investigated, and the results demonstrated that the Henry's law constants increased as temperature was increased and decreased as surfactant concentration was increased. The decrease in the Henry's law constants became obvious above the critical micelle concentration. The effect of surfactant addition on the Henry's law constant was larger for the more hydrophobic species. The micelle-water partitioning coefficients (K-mw) for the chlorinated ethylene-surfactant pairs were estimated from the Henry's law constants. The values of K-mw estimated from the Henry's law constants at high surfactant concentrations had a small standard error. On the basis of the experimental data, equations to estimate Henry's law constants in air-aqueous surfactant systems as a function of temperature and surfactant concentration were constructed. All of the equations estimated the experimental data with R-2 values above 0.96.