The noise added to an electron stream by the interception of a fraction of the current has been studied experimentally at a frequency of 3 kMc/s. The electron beam was produced in a demountable vacuum system by a parallel-flow Pierce gun in a confining magnetic field. A series of circular apertures and mesh grids on a plate capable of being moved within the vacuum chamber allowed the interception of various fractions of the total beam current. The excess noise caused by interception was measured at the anode of the electron gun and at various points in a drift region.Interception noise caused by mesh grids was found to be of much greater magnitude than that caused by circular apertures. The absolute level of the excess noise and its variation with the strength of the confining magnetic field were found to be in reasonable agreement with existing theory as modified by the author.It was shown that current interception excites a standing wave of noise along the electron beam in the drift region. Measurements made on a temperature-limited electron beam have shown that interception noise can arise in a region where noise smoothing is a consequence of processes external to the electron gun.