The relevance of the work is caused by the need to obtain the detailed information on the effect of ultrasonic treatment on structural and mechanical properties of crude oils of West Siberian oil and gas province to solve the problems, arising in their recovery and transportation. The aim of the work is to determine the viscosity-temperature characteristics and energy parameters of the paraffinic and highly paraffinic crude oils treated in ultrasonic field; to establish the effect of sonication on formation and group composition of wax deposit in highly paraffinic crude oil. The methods of the investigation: rotary viscosimetry, pour point, cryoscopy in benzene, liquid-adsorption chromatography, method of «cold finger», wax deposit, FT-IR spectroscopy. The results. The authors have carried out the ultrasonic treatment of the highly paraffinic and paraffinic crude oils with the frequency of 24 kHz and a radiation intensity of 10 W/cm2. It was found that the ultrasonic treatment of the paraffinic crude oils leads to increase of rheological parameters (viscosity and shear stress), heat of viscous flow activation, energy of destruction of the oil dispersed systems, pour point and amount of wax deposits. After sonication in the sediment of the highly paraffinic crude oil, the proportion of high-molecular n-alkanes increases and the mass fraction of asphaltenes and their average molecular weight decreases. The ultrasonic treatment of the paraffinic crude oil leads to improve the viscosity-temperature and energetic characteristics at the optimal exposure time. The studies showed that the ultrasonic treatment, as well as any other method, might be both the most effective and give a negative result. Short-term treatment (30 sec) of the paraffinic crude oils with high content of resin-asphaltene components leads to significant reduction in viscosity, which will reduce the price of hydrocarbons at production and transport. Sonication of the paraffinic crude oil leads to increase of viscosity and pour point. However, highly paraffinic crude oils, heated by the action of the ultrasound must be transported before the beginning of crystallization of the paraffinic hydrocarbons.