The most emerging technology of sensor networks is the use of them in the medical care to save patients lives, create valuable data for medical research, and cut the cost of medical services. Recently, body sensor networks are used for remote health monitoring and patient care. This book, therefore, attempts to provide of unified overview of broader field of Wireless Sensor Networks in healthcare applications. The organization of the book starts with the background of wireless sensor networks, and then completes description of the patient health metrics: heart rate and blood oxygen saturation (SpO2) by using body sensor networks for better treatment. In this book the idea of architecture of wireless sensor networks is presented for the monitoring of patients different health metrics: heart rate and blood oxygen saturation levels for treatment at home. The main focus of book is to examine, monitor and analyze patient heart beat activities and oxygen saturation level in order to meet better treatment and health care. In addition this book provides countermeasures of different security attacks related to data gathering from different sensors.