The differential equations for heat transfer from vertical plates in free convection were rederived in dimensionless form and extended to include inclined plates. The analysis indicated that the only change in the plate was the component of the gravitational force in the plate surface direction. The limitation of the equation is that the flow be laminar and two-dimensional. Heat transfer from a flat plate in free convection was studied at angles of inclination ranging from 0 to 40 deg measured from the vertical, for a range of Grashof numbers from 106 to 109 and temperature differences from the surface to the surroundings of 200 to 260 F. The investigation shows the inclined-plate nondimensional unit thermal conductance, Nu, can be predicted from vertical plate conductances. The Grashof number in the Nusselt relation for the vertical plate, when modified by the cosine of the angle of inclination, can predict the inclined-plate conductances to within 10 per cent of those determined experimentally.