In order to fully exploit the analytical capabilities of the proton microprobe, it is desirable to be able to raster the focused beam over large areas of the target without loss of resolution. This paper describes the Oxford microprobe scanning system, which has some novel and interesting features. The beam spot is rastered over the sample using a fast vertical scan and a slow horizontal scan. The fast deflection is produced by two coils situated before the lens system, orientated so that the deflection occurs in the plane of minimum aberration. The slow deflection is achieved by unbalancing the currents in the coils of the last quadrupole in the focusing system. This has the effect of inducing a dipole field inside the lens, which causes the beam to be deflected with little increase in aberration. This system enables the beam to be rastered over areas from 20 μm × 20 μm to 4 mm × 4 mm. Calculations and experimental evidence indicate that for undeflected beam spot sizes of 1 μm × l μm, even for the 4 mm × 4 mm scans, the broadening at the extremities of the scan is no more than 10 μm.