Although of established value in industrial and military usage, the potential of thermography as a clinical diagnostic technique has yet to be fully recognised. First used clinically in the diagnosis of breast disease, medical thermography has many other applications. These include the assessment of the severity of burn injuries and of tissue viability, the diagnosis of deep vein thrombosis, and of cutaneous malignant melanoma, the identification of carotid arterial disease, and of bone metastases, and the monitoring of drug therapy in rheumatology and in peripheral vascular disease. The suitability of thermography to the specific needs and problems in each of these clinical areas is outlined briefly, and the place of medical thermography in modern diagnostic imaging discussed.