Applications of couple stress and micropolar theories to the problems of oscillatory flow in a circular tube are discussed. Couple stress and spin angular momentum are considered in this approach. The exact solutions for velocity, micro-rotation, vorticity, shearing stress, flow rate and energy dissipation are obtained mathematically. And the energy dissipation over the cross section are calculated numerically. These solutions are characterized by three parameters. One is dimensionless frequency W which is called Womersley number. The others are the ratios of viscosities ε and the size effect parameter λ which do not appear in Newtonian fluid. ε is the ratio of vortex viscosity to shearing viscosity. λ gives the relation of the size between the corpuscle and the tube radius. The solutions are compared with those for Newtonian fluid and investigated with variations of ε and λ.