Abstract: A method for utilizing a silencer unit attached to an exhaust tube in a large diesel engine, and an exhaust gas system for applying the method in practice, in which the silencer unit includes a substantially hollow, preferably cylinder formed body member, inside of which a set of sound silencing porous elements can be fitted, said elements including a flow channel for the exhaust gases and being arranged in successive order in the flow direction of the exhaust gases longitudinally of the body member so that the exhaust gases are led through the flow channel of each element one after the other. Said elements are installed inside the body member in the axial direction from one end thereof one at a time and are supported to the inner mantle surface of the body member. In the flow direction upstream of the body member the exhaust tube is provided with means for feeding a medium containing ammonium, urea or the like reagent applicable for catalytic depuration into the exhaust gases.