This book is intended as an introductory text for Engineering and Applied Science Students to the Medical Applications of Electronics. A course has been offered for many years in Cardiff in this arena both in this College and its predecessor institution. A new group, the Medical Systems Engineering Research Unit, was established following the reorganisation of the College. Restructuring and review of our course material and placing the responsibility for teaching this course within the new group led to a search for new material. Whilst we found a number of available texts which were suitable for aspects of our new course, we found a need for a text which would encompass a wide scope of material which would be of benefit to students completing their degree programmes and contemplating professional involvement in Medical Electronics.