Thoracic radiotherapy has an established role in the management of limited-disease small-cell lung cancer (LD SCLC). However, essential questions relating to the optimisation of thoracic radiotherapy remain unanswered, including volume of irradiation, optimal total dose, fractionation, timing and sequencing of radiation. This review highlights the need for well-designed multi-national trials aimed at the optimisation and standardisation of radiotherapy for LD SCLC.