A method is described for the quantitative determination of the three groups of constituents-asphaltenes, oils, and resins-in petroleum and native asphalts. The asphaltene fraction is obtained by extracting the asphalt with normal pentane. The pentane soluble portion is further fractionated by adsorption on anhydrous alumina and extraction first with pentane to obtain the oil fraction and then with a methanol-benzene solution to obtain the resin fraction. Unlike most proposed methods, the three asphalt constituents are recovered and may be used for further study. A complete analysis can be made in one eight hour day after the sample has been dispersed in pentane and allowed to stand approximately 12 hours or overnight.