The authors study numerically, by using an implicit centred finite difference method with non-uniform grid, the effects of inclination on the evaporation of liquid film flowing on a horizontal or inclined isotherm, flat plate with the assumption of existing two-dimensional laminar boundary-layers with variable physical properties. In the case of an humid air-water system, they compare their results with those of other authors and study the influence of the entrance air velocity and the inclined angle of plate. They show that for an isotherm plate, the inclined angle effects heat and mass transfer, especially for low flow air velocity and for an inclined angle less than 10 degrees. In this domain, the interfacial temperature is so high as the inclined angle increases which causes an increase of the density of flux of vapor, of the latent heat of vaporization and a reduction of draining length. For the heated plate, it is always for an inclined angle less than 10 degrees, that the effects of this parameter and air velocity are very important on the film thickness and its interfacial velocity. Opposite to the case of an isotherm plate, air velocity increase causes a reduction of interfacial temperature; inclined angle has less effect an temperature, density of latent heat of vaporisation and on heat and mass transfer at the interface. Generally, for an isotherm or heated plate, heat transfer is dominated by liquid-vapor phase transition.