It is now established that the treatment of choice for limited small-cell lung cancer (SCLC) in the United States, Canada, and Japan is thoracic radiotherapy (TRT) combined with etoposide (VePesid), either alone or in conjunction with other agents, especially a platinum agent. The specific factors related to the use of TRT in the treatment of limited SCLC are: (1) dose (total and daily), (2) volume to be irradiated, (3) fractionation, (4) timing of radiation relative to chemotherapy (concurrent, at the same time; alternating, using both within weeks; or sequential, all of one followed by all of the other without any overlap), (5) whether radiation should be given earlier or later in the treatment course, and (6) whether to use a split course (rest intervals during a course of radiotherapy) or a continuous course of radiation. This paper discusses each of these factors.