The effect of receiving water salinity on the effectiveness of two oil dispersants, Corexits(R) 9527 and 9500, was investigated using a recently implemented modified version of the Swirling Flask efficacy test, The dispersants were tested with ten different oils, representing a wide range of physical-chemical properties. Test salinities ranged from 0 to 35 ppt, with temperature held constant at 15 degrees C. Results showed Corexit 9500 to be generally more effective on most of the dispersible oils at most salinities, but performance of both products was significantly affected by salinity. Both dispersants performed best at salinities above 25 ppt, with Corexit 9500 maintaining its effectiveness over a fairly wide range of salinities. Correlations between dispersant effectiveness and various oil physical/chemical properties were highly variable.