Dimethylsulfide (DMS) concentrations measured twice per hour in marine boundary layer air at the Cape Grim baseline station exhibit high variability over timescales as short as several hours. Major sources of this variability are identified as a diurnal cycle associated with the daytime destruction of DMS by reaction with hydroxyl radical, and a strong dependence upon wind speed, with high DMS concentrations at high wind speeds. The wind speed dependence was found to be broadly consistent with the wind speed dependence proposed by Liss and Merlivat [1986> for 10 m wind speed in the range 3.6 to 13 m s-1. ¿ American Geophysical Union 1995.