A helmet liner adapted to be conformed to an inner surface of a helmet to cushion in use the rear of a wearers head from the helmet is described. The liner comprises a plurality of elongate grooves comprising at least one longitudinal groove configured to extend in use along a longitudinal direction between the nape of a wearers neck and the crown of the wearers head, and at least one lateral groove adapted to extend in use at least partially around the head of the wearer in a lateral direction between the wearers ears. The at least one longitudinal groove is deeper than the at least one lateral groove.
