A watertight lighting fixture, comprising a casing (10), which is closed by a tempered glass (11) at a light emission surface and which has at its ends respective heads (12), connected and fixed to said casing (10); in particular, a slide (14) is placed within said casing (10), on said slide (14) are fixed the wiring terminals (15) of the fixture and below said slide (14) is placed a reflector (16), which is able to spread light outside and which is placed in correspondence of at least one light source, such as at least one neon tube (18) or a plurality of LEDs (17).