Abstract: In this work, the characterization of the radio channel for ISM 2.4GHz Wireless Sensor Networks (WSN) for Judo applications is presented. Judo is an Olympic sport, in which the International Judo Federation (IJF) gives assistance and guidelines for the organizers of international competitions. Following IJF rules, the environments where Judo competitions are held are complex indoor scenarios in terms of radiopropagation, as some competition venues have large spectator capacity, multiple competition areas, furniture, and other facilities. The electromagnetic interference within the scenario is also an important issue, as personal portable devices, wireless microphones and other wireless communication systems used by the media are present. For the assessment of the impact that the topology and the morphology of these environments have on electromagnetic propagation, an in-house developed 3D ray-launching software has been used. Time domain results as well as estimations of received power level have been obtained for the complete volume of the scenario, which have been compared with measurements. The measurement campaign has been carried out deploying ZigBee-compliant XBee-Pro modules at a local Judo club's facilities, emulating a competition/training venue with a contest area with the dimensions specified by the IJF for international competitions, and using approved Judogis (jacket, trousers and belt). The analysis is completed with the inclusion of in-house human body computational model. The presented analysis can aid in the optimal network deployment, making the use of WSNs attractive for multiple applications in this kind of environments, as helping referees, monitoring vital signs, anti-doping control or Judoka identification.