Some acute effects of inhalation exposure to toluene, 1,1,1-trichloroethane (1,1,1-TCE), halothane, and ethanol were examined in mice. Lethality and performance on an inverted screen test of motor performance were measured following 10-, 30-, and 60-min exposures. Concentration-dependent effects were obtained on both measures for all solvents except that lethal concentrations of ethanol could not be produced under these exposure conditions. Lethality increased with longer exposures for toluene, 1,1,1-TCE, and halothane. Sensitivity to the motor effects of 1,1,1-TCE, halothane, and ethanol increased when exposure duration was increased from 10 to 30 min, with no further change with 60-min exposures. In contrast, behavioral sensitivity to toluene increased over the entire range of exposure durations. The relative lipid solubilities of the solvents correlate with potency for behavioral activity but not as well with potency for lethality. The ratio of potency for motor and lethal effects depended on the chemical studied and in some cases exposure duration. These results demonstrate that both concentration and exposure duration determine the effects of inhaled compounds, but a simple linear relationship does not exist and it depends upon the effect measured.