In this research, the deflection in the interface of a partially composite beam considering the effect of shear deformation is deter-mined. The system of beams is structured by two beams of prismatic sections, connected by an adhesive very thin and rigid, subjected to a uniform bending moment and a uniformly distributed load. The governing differential equation of the partially composite beam is obtained from the total functional energy that takes into consideration the shear deformation. The extreme moments creating second moments, shear forces and normal forces are applied to each beam. The differential equation is derived and then, compared to the one found in partial composite beams where the shear deformation is neglected. It is shown that the theoretical results of deflection with and without shear deformation are compared to each other and also with those found in the Timoshenko’s beam theory.