Measurements on the drainage of several mineral oils and a diester from vertical metal surfaces of different roughnesses have been carried out. Metals studied were low-carbon steel, aluminum, and silver-copper alloy (90 Ag-10 Cu). The method was adapted from one devised by Bikerman and applied by him to stainless steel, in which mineral oil retention by rough surfaces was compared with retention by smooth surfaces. High correlation has been obtained between surface roughness, as measured by a stylus instrument, and thickness of an apparently stagnant layer of oil. The correlation is highest when the roughness is measured in the direction of drainage. Equations for calculating the total thickness and volume of fluid retained by smooth surfaces have been reconfirmed.Contributed by the ASLE Technical Committee on Properties of Lubricants and presented at the Annual Meeting of the American Society of Lubrication Engineers held in Chicago, Illinois, May, 1964.