The ionic conductivity of undoped and doped PbFBr crystals is reported. Measurements were performed parallel and in some instances perpendicular to the crystallographic c-axis. Furthermore, results on aliovalent doped pressed pellets are presented. The influence of inevitably present oxygen impurities and deviations from molecularity is discussed in conjunction with the role of deliberately added aliovalent metal halides. In accordance with a model developed for PbFCl the mechanisms of mass transport in PbFBr are proposed and related with observed conductivity activation enthalpies.