The Hall coefficient and conductivity have been measured during pile‐irradiation for a number of zone‐refined,p‐type silicon crystals with initial resistivities of 1, 8, and 100 &OHgr;‐cm. To supply the magnetic field for the Hall measurements, a small electromagnet was used. The conductivity of zone‐refined silicon shows much faster changes with irradiation than pulled silicon samples of equivalent resistivity. The 100‐&OHgr;‐cm samples exhibit a monotonic nonlinear decrease of ln&sgr;, conductivity, vs &phgr;f, integrated fast flux, whereas the other samples with initial Fermi levels closer to the valence band have one or two regions of linear decrease in ln&sgr; vs &phgr;fbefore the nonlinear decrease region is observed. The Hall mobility for the 100‐&OHgr;‐cm samples decreases and becomes negative as a result of the carrier density decreasing with irradiation. In the case of the 8‐&OHgr;‐cm sample, the Hall mobility decreases with irradiation whereas the 1‐&OHgr;‐cm sample shows no change in Hall mobility with irradiation up to the maximum integrated flux used in the present experiment. The origins of the dependence of ln&sgr; on &phgr;fas well as the behavior of the Hall coefficient and Hall mobility with irradiation are discussed.