Networking with various healthcare devices on human body is one of the targeted applications of the IEEE 802.15.6 standard. Among those, human body communication is considered to have better performance in terms of power consumption and security for implanted and swallowable devices. Different from general applications of BAN, healthcare device network with implanted/swallowable devices requires a better understanding of the necessary time delay for the emergency messages transmission. In this article, we analyzed the delay of emergency message transmission based on IEEE802.15.6 at HBC. Both theoretical analysis and simulation were employed to calculate the average and shortest transmission delay, and also the distribution of the transmission delay at multi-user multi- UPs for slotted Aloha access protocol.