This paper thoroughly analyses the HIPERLAN MAC protocol, which is a standard for wireless local area networks (WLANs) defined by the European Telecommunications Standards Institute (ETSI). Since the HIPERLAN MAC protocol belongs to the class of carrier sensing multiple access with collision avoidance (CSMA/CA), we analyze the HIPERLAN stability problem. We also present an in depth performance analysis, by simulation, of the HIPERLAN MAC protocol. The analysis is performed by considering data traffic patterns (advanced data traffic) which have a very similar shape to traffic generated by WWW applications. Furthermore, in the analysis we consider Poissonian data traffic too. Our conclusion is that the HIPERLAN MAC protocol performs satisfactorily, although performance measures with advanced traffic are worse than the corresponding performance measures with Poissonian traffic. Furthermore, we broadened our analysis to include the influence of the packet lifetime and channel access priority mechanism on the performance measures provided by HIPERLAN.