Our recent measurements of the concentrations of CS2 in the background troposphere suggest that the atmospheric residence time of this substance is short, probably on the order of ten days. This conclusion is based on the very low CS2 concentrations found in the free troposphere (<3 pptv) and the relatively large concentrations (30 pptv) found in the boundary layer. Such a rapid decrease in concentration with altitude can be explained in a straight-forward way only if the residence time of CS2 is less than the characteristic vertical mixing time of the troposphere, which is of the order of ten days.