Over the past decade, the design and development of wearable sensors for biomedical applications has garnered considerable attention in the scientifi c community and in industry. This chapter aims to review research conducted into wearable sensors for healthcare monitoring. Acceptance of this approach in observation of physiological data depends strongly on the cost, wearability, usability and performance of such devices. An outline of body sensor network systems (and applications of wearable computing devices) is provided with a summary of electronic textiles. A synopsis of the clinical applications of this type of technology is given at the end of the chapter © 2012 Woodhead Publishing Limited All rights reserved.