This theoretical and experimental study deals with heat transfer mechanisms between the two rings of a cylindrical roller bearing. Theoretical analysis concerns conduction heat transfer at the interfaces of the roller-rings. Rolling thermal conductance is modelled in the angular area of radial load distribution (double rolling contact area). This modelling is based on the dynamic macroconstriction phenomenon. Contact areas between rollers and rings are determined using Hertz's theory. Results show the influence of rotational speed, radial load and diametral clearance. Concerning the experimental results, heat transfer is modelled by a global thermal conductance which takes into account the three modes of transfer (conduction, convection and radiation). Knowing the temperature fields inside both rings of the bearing and in the heating device (filament resistance), thermal conductance may be estimated. For that purpose, a 2D inverse technique is used. Experimental results are presented for a rotational speed N −2 .K −1 for the NU 208E G15 roller bearing. Theoretical results are very high compared to the experimental ones. This difference is due to the important hypothesis of smooth contact in Hertz's theory, which involves smaller constriction resistance.