Current technological advances in sensors, power efficient integrated circuits, and wireless transferring have allowed the development of miniature, lightweight, low-cost, and smart physiological sensor nodes. These sensor nodes have capacity of sensing, controlling, processing, and communication one or more vital signs. Furthermore, they can be used in wireless personal area networks (WPANs) or wireless body sensor networks (WBSNs) for health monitoring. Many studies were performed and/or are under way in order to develop flexible, reliable, secure, real-time, and power-efficient WBSNs suitable for healthcare applications. This paper reviews the applications of wireless sensor networks in the healthcare area and discusses the related issues and challenges. It reviews some applications of WSNs developed or currently being developed for health monitoring.