Crude oils and asphaltene-resin-wax (ARW) deposits from long-developed fields of Tatarstan, Orenburg oblast, and Kyrgyzstan were investigated by means of differential scanning calorimetry. The appearance of the crystalline phase of high-molecular-mass hydrocarbons with mp at about 55C was revealed in the oils. It was shown that the crystalline phase of the oils consisted of higher paraffin hydrocarbons of a fairly homogeneous composition with mp > 90C coprecipitated with asphaltenes. In the ARW deposits, the crystalline phase was represented in the form of separate microcrystal hydrocarbon particles, as well as associated with asphaltenes.