The patient monitoring system is one of the essential medical systems to help medical team monitoring the vital signs of patients for 24 hours and giving emergency treatment at the critical abnormal condition. Recently, Wireless Body Area Networks (WBANs) are applied to this situation for making the patients comfortable and the medical team convenient. However, existing candidate MAC protocols for WBAN are not appropriate to satisfy the requirements of the patient monitoring systems. To resolve this issue, we propose a Data Profile-based Contention-free MAC (DPC-MAC) protocol, which can synchronize the slave nodes by piggybacking synchronization information to ACK/NACK packets without beacon packet transmission. In addition, the DPC-MAC schedules the superframe resources based on the data profile of slave nodes. Through the performance comparison, the proposed DPC-MAC protocol radically reduces the average latency, extends the network lifetime, and diminishes the average link occupancy compared to the existing candidate MAC protocols.