Lighting device for vehicles, in particular a headlight or headlamp, comprising: - a housing body defining a rear mounting seat for at least one light source; - a lens arranged at the front of said housing body; and - a cover, which can be coupled in a releasable and fluid-tight manner to said housing body; said rear mounting seat being closed in use at the rear by said cover, on the side opposite the one of said lens wherein i) said cover defines, at the rear of said rear mounting seat, a chamber housing in use at least one drying material for absorbing any moisture in the environment inside the housing body; ii) said cover has a symmetry axis and comprises a radially outer circular side wall for a fluid-tight coupling with said rear mounting seat characterized in that, in combination iii) an annular edge projects axially from said mounting seat; said cover comprises an annular lip flexible in a radial direction, outwards with respect to said axis; said annular lip and said circular wall defining between them an annular seat, which is an axial and radial abutment for the annular edge; iv) said annular lip being configured to define in use an axial and radial locking of said cover on said mounting seat; v) said annular lip is designed to receive said annular edge within said annular seat with a radial clearance; said radial clearance being small enough to be annulled as the result of a radial flexion towards the outside of the annular lip following to an axial thrust exerted against said cover in a direction of insertion of the cover into said mounting seat. - a housing body defining a rear mounting seat for at least one light source; - a lens arranged at the front of said housing body; and - a cover, which can be coupled in a releasable and fluid-tight manner to said housing body; said rear mounting seat being closed in use at the rear by said cover, on the side opposite the one of said lens wherein i) said cover defines, at the rear of said rear mounting seat, a chamber housing in use at least one drying material for absorbing any moisture in the environment inside the housing body; ii) said cover has a symmetry axis and comprises a radially outer circular side wall for a fluid-tight coupling with said rear mounting seat characterized in that, in combination iii) an annular edge projects axially from said mounting seat; said cover comprises an annular lip flexible in a radial direction, outwards with respect to said axis; said annular lip and said circular wall defining between them an annular seat, which is an axial and radial abutment for the annular edge; iv) said annular lip being configured to define in use an axial and radial locking of said cover on said mounting seat; v) said annular lip is designed to receive said annular edge within said annular seat with a radial clearance; said radial clearance being small enough to be annulled as the result of a radial flexion towards the outside of the annular lip following to an axial thrust exerted against said cover in a direction of insertion of the cover into said mounting seat. i) said cover defines, at the rear of said rear mounting seat, a chamber housing in use at least one drying material for absorbing any moisture in the environment inside the housing body; ii) said cover has a symmetry axis and comprises a radially outer circular side wall for a fluid-tight coupling with said rear mounting seat characterized in that, in combination iii) an annular edge projects axially from said mounting seat; said cover comprises an annular lip flexible in a radial direction, outwards with respect to said axis; said annular lip and said circular wall defining between them an annular seat, which is an axial and radial abutment for the annular edge; iv) said annular lip being configured to define in use an axial and radial locking of said cover on said mounting seat; v) said annular lip is designed to receive said annular edge within said annular seat with a radial clearance; said radial clearance being small enough to be annulled as the result of a radial flexion towards the outside of the annular lip following to an axial thrust exerted against said cover in a direction of insertion of the cover into said mounting seat.