This paper presents a wireless vital sign monitoring system using IEEE802.15.4a standard based on ultra wideband (UWB) wireless communications. The vital signs are categorized into continuous and routine vital signs; the continuous signs include electrocardiogram (ECG), and the routine ones cover blood pressure, oxygen saturation, and body temperature. To conduct both tasks simultaneously, a superframe structure is optimized to minimize the delay time of packet transmission through computer simulation. Results showed that IEEE802.15.4a standard has capability to together monitor both single continuous sign and multiple routine signs simultaneously.