Study of the coexistence between ZigBee and Wi-Fi IEEE 802.11b/g networks in the ISM band The number of wirelessly connected multimedia devices and different communication standards, supported by these devices, is rapidly increasing. However, the appropriate frequency bands (licensed and unlicensed) for data transmission by these standards are very limited. The rising density of wireless networks and their coexistence in the same or adjacent radio frequency (RF) spectrum can significantly decrease the quality of provided services. This paper deals with the study of coexistence between ZigBee (IEEE 802.15.4) and Wireless Fidelity (Wi-Fi) networks, including the IEEE 802.11b/g standards, which operate in the unlicensed Industrial, Scientific and Medical (ISM) band at 2.4 GHz. Firstly, a general simulation model was developed. Secondly, to verify results from simulation by measurement, an appropriate laboratory workplace in anechoic chamber was proposed and realized. Such setup and the measurement principle are briefly described in this paper too. Impact of the IEEE 802.11b/g networks on the ZigBee and vice versa is evaluated by dependence of bit error rate (BER) and error vector magnitude (EVM) on the power imbalance between power levels of considered RF signals, respectively.