Thermoluminescent dosimeters are used in a variety of medical applications including radiation therapy, diagnostic radiology, and radiotherapy mailed dosimetry. For many years LiF:Mg,Ti has been dominating the field, of TL medical dosimetry. In recent years, however, a relatively new material, LiF:Mg,Cu,P, has attracted the attention of the medical dosimetry community and its usefulness in a variety of applications was demonstrated. In this article we discuss and explain in detail the dosimetric properties of these two materials, emphasizing the characteristics that are particularly relevant to medical dosimetry, with special emphasis on the sensitivity (including fading) dose response, and the photon energy dependence. (c) 2007 Published by Elsevier Ltd.