This paper describes a developed continuous patient monitoring system based on the ZigBee protocol. The system was tested in the hospital environment using six sensor devices in two different modes. For electrocardiogram transmission and in the absence of hidden-nodes, the system achieved a mean delivery ratio of 100% and 98.56%, respectively for star and 2-hop tree network topologies. When sensor devices were arranged in a way that three of them were unable to hear the transmissions made by the other three, the mean delivery ratio dropped to 83.96%. However, when sensor devices were reprogrammed to transmit only heart rate values, the mean delivery ratio increased to 99.90%, despite the presence of hidden-nodes.