In this study, flow of an incompressible MHD third grade fluid in an inclined cylindrical pipe and entropy generation are considered. The nonlinear momentum and energy equations for the flow presented. Regular perturbation technique employed for the solutions. The effects of some thermo-physical parameters examined. Results show that increase in the third grade parameter and the Grashof number increases both the velocity of the fluid flow and the temperature of cylindrical wall, while increase in the magnetic field parameter reduces the flow velocity. Results further show that in the third grade parameter and the Brinkman number indicates increase in temperature which enhances entropy generation number. The magnetic field parameter suppresses the temperature of the system thereby reduces entropy generation number.