Gyarmati's variational principle developed on the thermodynamic theory of irreversible processes is employed to study the viscous dissipation effects with uniform suction and injection on the infinite flat plate. The velocity and temperature fields inside the boundary layer are approximated as simple polynomial functions, and the functional of the variational principle is constructed. The Euler Lagrange equations are reduced to simple polynomial equations in terms of velocity and thermal boundary layer thicknesses. The velocity, temperature profiles, skin friction and heat transfer with the viscous dissipation effects are analyzed and are compared with known numerical solutions. The comparison of the present solution with the existing solutions establishes the fact that the accuracy is remarkable.