To describe the hydrodynamics, the tidal inlet system is schematized to a basin connected to the ocean by a prismatic channel. Velocities in the prismatic part are uniform in the longitudinal direction. In deriving the equation of motion, depth variations with tidal stage are included. The continuity equation is based on the assumption of a uniformly fluctuating basin water level. To find analytical solutions, the bottom friction term is linearized, thus non-linearities only result from depth variations with tidal stage, and the ocean tide is simple harmonic. The resulting equations are solved using a perturbation technique resulting in a set of leading order and first order equations. At leading order, non-linear terms are absent and the solution consists of harmonics with the frequency of the ocean tide. At first order, non-linear terms exist, resulting in solutions with harmonics having twice the frequency of the ocean tide (even overtides). The combination of the fundamental frequency and the even overtides results in tidal asymmetry. In addition to even overtides, a mean velocity in the ebb direction and a basin level set-up are present. The solutions are applied to the representative inlet and where possible compared to the …szoy-Mehta solution.