In this paper we investigate the properties of the PROFIBUS MAC protocol when operated over error prone links, like wireless links. In order to show that the protocol is very sensible to loss of control frames (e.g. token frames) we evaluate three performance measures, using a simulation approach: the mean delay, the mean station outage time and the cumulated outage time, i.e. the fraction of time where a single station is not member of the ring due to loss or error of control frames. The results indicate that the PROFIBUS MAC protocol is not really a good choice for use over error prone links.