The invention relates to a damp-proof luminaire having a trough-shaped housing (2), which is provided with a circumferential marginal groove (18), having a transparent cover (4), which covers the open side of the housing (2), whose circumferential marginal region (8c) enters into the marginal groove (18) of the housing (2) and which is connected to the housing (2) detachably by a plurality of closure apparatuses (3), which are arranged distributed over the circumference, and terminals located in the housing (2) for luminous means (6). In order to improve the protection against the ingress of water in the region of the partition joint between the housing (2) and the cover (4), the marginal region (8c) of the cover (4) bears with at least one marginal edge against the groove wall or the groove rim.