The magnetoresistance effect was investigated in high-purity zone-refined AgBr in order to obtain information about the conduction band structure in this material. The measurements were performed at 2°K and in magnetic fields up to 18 kG. The rate-of-drift method using a sensitive electrometer was employed to observe the transient photoconductivity both in the presence and absence of a magnetic field. Results of the experiments are consistent with the assumption of a spherically symmetric conduction band centered at k=0 as well as with an electron relaxation time of the form: τ=τ0(∊KT)32, with τ0=1.1×10-12 sec. During the course of the magnetoresistance measurements, a deviation from Ohm's law at high electric fields was noted. Some data on this "hot electron" effect are presented and briefly discussed.