Atmospheric concentrations of OCS were measured in the Southwestern and Eastern United States. The average concentrations were 435¿54, 454¿31 and 511¿36 parts-per-trillion by volume at Philadelphia, Pa., Wallops Island, Va. and Lawton, Okla., respectively. The data suggest that the lifetime of OCS is much longer than common atmospheric sulfur gases such as H2S and SO2, and that the OCS sources are diffuse and are not concentrated in urban areas. The transport of OCS to the stratosphere from the troposphere may be an important source of stratospheric sulfur. ¿ 1977 American Geophysical Union