Concentrations of oil accommodated in sea water under laboratory conditions are directly related to the amount added and the degree of turbulence, but inversely related to temperature. The major fraction (87–98%) of this oil is in particulate form ranging in size from about 1 to 30 μ, presumably small droplets. The exact ratio of the particulate to subparticulate fractions is directly related to the apparent viscosity of each individual oil. Of the total amount of oil initially added, 9–15% appeared in sea water at the end of the 7-days experiments. Except in the proximity of recent oil slicks, the oil concentrations observed in these experiments are one to two orders of magnitude greater than the concentrations generally observed in the marine environment off eastern Canada.