A procedure involving iteration of the differential approximation (Milne-Eddington) solution is used to carry out radiative transfer calculations for the following problems: (1) a heat-generating, gray medium contained between concentric spheres, and (2) a spherical region of constant heat generation imbedded in an infinite, gray medium. The first iteration yields an approximate solution which compares favorably with other approximate solutions in simplicity, range of applicability, and accuracy. © 1969.