The effect of noncondensables upon the laminar film condensation of vapor-gas flow inside a horizontal tube were investigated. The analysis was undertaken for the continuity, momentum and the thermal energy with its boundary conditions for the condensable film. Also the diffusion equation with its boundary conditions for the gas phase. The resulting partial differential equations were solved numerically by finite difference technique using a computer program for a wide range of parameters. Numerical results were obtained for the heat transfer coefficients with and without noncondensable for a wide range of parameters. It was found from the numerical results that the heat transfer coefficients inside the tube of the horizontal condenser are strongly dependent upon the axial and circumferential position. The noncondensable reduces the heat transfer and these reductions are accentuated at low operating pressures. For small steam velocities, a severe effects of the noncondensables are expected at the back end of the tube.