Heat transfer measurements are reported for the film condensation of pure steam on a thick-walled horizontal tube. The thermal resistance of the tube in these tests was approximately 3 times that of the condensation film. Significant circumferential temperature gradients were measured around the tube, with the magnitude of the variation exceeding that of the average vapor-to-wall temperature difference. The results were found to be in close agreement with a numerical model for condensation on a nonisothermal surface and also with the correlations proposed by Fujii for the surface temperature distribution under uniform heat flux conditions. The heat flux through the condensate film was found to be uniform within the region 0 degrees-165 degrees but decreased where the condensate film thickened abruptly on the underside of the tube, where droplets were being formed.