An experimental determination of the single-particle mean kinetic energies for 3He along the T = 2.00 K isotherm in the dense liquid and in the solid hcp and bcc phases is reported. Deep-inelastic neutron scattering measurements at exchanged wave vectors ranging from 90.0 to 140.0 A(-1) have been performed in order to evaluate, within the framework of the impulse approximation, the molar volume dependence of the kinetic energy. The results are found in excellent agreement with recent diffusion Monte Carlo simulations.