We compute models of rotating neutron stars, emphasizing on calculating the mass increase due to differential rotation induced by the radial pulsations of the model(s). A brief description of our numerical approach has as follows. First, the unperturbed Oppenheimer-Volkoff equations are solved for several polytropic and realistic equations of state. Then, uniform rotation is inserted into the models in accordance with the Hartle's perturbation method (see, e.g., Hartle 1967; Hartle and Thorne 1968). At this stage, corrections to mass and radius, owing to spherical and quadrupole deformations, are calculated. Third, the perturbative approach to the structure of the model(s) up to terms of third order in angular velocity (see, e.g., Benhar et al. 2005) is carried out; angular momentum, moment of inertia, rotational kinetic energy, and gravitational potential energy are some of the quantities corrected drastically by such third order approach. Finally, differential rotation driven by the radial pulsations of the model(s) and the corresponding increase in mass (see, e.g., Hartle 1975; Hartle and Munn 1975) are calculated. Such a mass increase is discussed within the framework of its connection with the corresponding pulsation energy of the model(s) (see, e.g., Meltzer and Thorne 1966). REFERENCES: Benhar, O., Ferrari, V., Gualtieri, L., and Marassi, S. 2005, Phys. Rev. D, 72, 044028. Hartle, J. B. 1967, Ap. J., 150, 1005. Hartle, J. B. 1975, Ap. J., 195, 203. Hartle, J. B., and Munn, M. W. 1975, Ap. J., 198, 467. Hartle, J. B., and Thorne, K. S. 1968, Ap. J., 153, 807. Meltzer, D. W., and Thorne, K. S. 1966, Ap. J., 145, 514.