Eucalyptus microcarpa, or grey box, is a species of Eucalyptus which is endemic to Australia. Alternative common names for this species include gum-topped box, inland grey box, narrow-leaved box, and western grey box. It is a spreading tree which has fibrous grey bark on the trunk and lower branches, but has smooth, grey-brown bark on its upper branches The flower buds have conical caps and the flowers themselves, which appear from late summer to winter, are cream coloured.