We report on the field emission from self-assembled silicon nanostructures fabricated on n-type silicon (100) substrates using electron beam annealing. Arrays of nanostructures with an average height of 8 nm were formed by substrate annealing at 1100 °C for 15 s. Simple field emission diode structures were fabricated using these nanostructured silicon substrates as cathodes separated from an aluminium anode by a 1 μm thick layer of photoresist. The dielectric leakage current was less than 0.4 nA which was found to be a negligible component of the field emitted current flowing through the diode. Following conditioning, the Si nanostructure field emission characteristics become stable and reproducible with Fowler–Nordheim tunneling occurring for fields as low as 3.2 V μm-1. At higher fields, current saturation effects are observed with current-field characteristics typical of space charge limited conduction. The low voltage operation of this device results in suppression of ionizing electron–molecule collisions and the diode has thus been shown to work well at atmospheric pressure.