Wireless technologies are spreading also to safety-related applications. Wireless communication is realised by sending messages bit by bit from transmitter to receiver (serial mode communication). This resembles quite much the method used in field buses. There are already several field buses, which are validated to be used in safetyrelated applications. Many similar risks are relevant also in wireless communication systems, but wireless systems introduce also some new risks and the probability of failures is often higher than in wired systems. When all the risks or threats are considered, safety requirements determined, adequate measures are applied to minimise risks and the system is validated, wireless communication can be relevant possibility in safety-related machinery applications.