In modern era wireless sensor networks used in many areas like military, engineering, surveillance, agriculture, healthcare, home etc. Healthcare is one of the most important areas where wireless sensor networks play an important role. In this paper a detailed review on wireless sensor networks in healthcare system is presented to find out the best communication technology and sensors used in healthcare system. Various sensors (pulse oximetry sensor, sweat rate sensor, glucose sensor, acceleration sensor and ECG electrode) are used in healthcare system are presented in this paper. Several communication techniques (Bluetooth, Zigbee, NFC, UWB and Wi-Fi) are used in healthcare system also discussed. Out of these all-communication technologies UWB is more powerful and widely used in recent time.