The value of infra-red thermography in a number of pathologies, notably rheumatology and vascular diseases, is becoming well established. However, the high cost of thermal scanners and the associated image processing computers has been a limitation to the widespread availability of this technique to the clinical community. This paper describes a relatively inexpensive thermographic system based on a pyroelectric vidicon scanner and a microcomputer. Software has been written with particular reference to the use of thermography in rheumatoid arthritis and vasospastic conditions such as Raynaud's phenomenon.