In an attempt to resolve discrepancies between previous absolute and relative rate measurements, the kinetics of the gas-phase reaction of NO3 radicals with dimethyl disulfide (CH3SSCH3) have been reinvestigated using a relative rate technique. The data obtained indicate that because of chemical complexities in the system, reliable relative rate constant data cannot be obtained and that the recent literature on absolute rate constants is to be preferred. ¿ American Geophysical Union 1988