This work considered the natural convection of a one-dimensional heat generation and viscous dissipation model of a Magnetohydrodynamics (MHD) third grade fluid in an inclined cylindrical pipe with radiation. The governing dimensional equations of the momentum and energy were first non-dimensionalized and then solved analytically using the Homotopy Analysis Method (HAM). The results obtained are displayed on graphs. From the graphs, we observe that increase in the grashof number leads to increase in both the velocity and the temperatue of the fluid. Also, the temperature of the fluid increases with increase in the radiative heat flux and drops gradually as the radiative heat flux decreases. The effect of various parameters on the velocity and temperature profiles are reported graphically for both cases of the extended models to elucidate special features of the solutions.Â