It is described a gasket for a valve of an internal combustion engine, having an axis and comprising an annular sealing element to be externally arranged on the valve and an annular support element, coaxially arranged on the sealing element to press it radially on the valve; the support element comprising a first annular component, internally cooperating with the sealing element, a second annular component, coaxially surrounding the first component, and snap coupling means between these components; the second component comprising an annular main body and an outer annular end flange; the main body further having an annular edge projecting towards the axis and defining an axial abutment for the first component; the snap coupling means comprising two or more hooking projections angularly equidistant about the axis, cantileverly extending from the annular edge towards the flange and cooperating in contact with the first component to abuttingly keep it against the annular edge.