Abstract: A helmet display system is provided comprising a display visor 3 located on helmet 1 on which helmet is also positioned image projection means for projecting an image via a holographic combiner 4 on the display visor 3. The helmet further comprises an anti-glare visor 2 which has optical transmission characteristics similar to those of a neutral density visor, with the exception that these characteristics are modified to compensate for the low transmission value of the display visor 3 to frequencies within a narrow waveband to which the combiner 4 is tuned. The invention provides a helmet display system which can be used in conjunction with an aircraft head-up display if required.