Wireless Sensor Networks are well identified in variety of domains. The revolutions in technology are expanding the reach of healthcare and ultimately making it available anywhere and anytime. Wireless Sensor Networks enabled doctors and physicians to remotely monitor the patients and provide them constant supervision and support. However, to realize the potentials of this technology, critical issues faced securing the data needs to be addressed. Healthcare monitoring systems not only perform the essential task of data collection but also play a vital role in data propagation to healthcare provider and maintaining the large databases on complex systems. Therefore maintaining the security and privacy of patient's highly sensitive information is key issue in the design and deployment of such systems. In this thesis work we propose an efficient key generation and key distribution algorithm that contributes towards some of the most pressing problems of security in low power sensor networks.