There was fulfilled a study of the effect of stresses applied to a specimen during the direct and reverse transformations in titanium nickelide shape memory alloy on the enthalpy of these transformations. A series of experiments realizing the martensitic transformations on cooling and heating under a constant shear stress (in torsion mode), same for both the direct and the subsequent reverse transformations has been carried out. Simultaneously were made the measurements of the shear strain and the differential thermal analysis, the methodology of which allowed obtaining estimates of the amounts of heat release and absorption. It was found out that with an increase in the stress from 0 to 100 MPa the enthalpy of the reverse transformation decreases by a factor of 2.5. It was noted that if the direct transformation is carried out under a stress, and the subsequent reverse transformation is performed after the specimen is unloaded, the heat absorbed during the reverse transformation decreases with the same stres