An arrangement for introducing a liquid medium, e.g. urea, into exhaust gases from a diesel combustion engine, which arrangement comprises: - a mixing chamber housing (7, 18) enclosing a mixing chamber (21A, 21B), said mixing chamber housing (7, 18) comprising an exhaust gases inlet for introducing exhaust gases into the mixing chamber (21A, 21B) and a mixture outlet for supplying a mixture of liquid medium and exhaust gases out of the mixing chamber (21A, 21B); the mixing chamber housing (7, 18) being formed by a top wall, an end cap and a baffle plate, wherein the exhaust gases inlet and the mixture outlet are provided in the baffle plate, i.e. the exhaust gases inlet and the mixture outlet are positioned at the same side of the mixing chamber housing (7, 18); - a liquid medium injection port for injecting liquid medium into the mixing chamber (21A, 21B); - a liquid medium housing positioned within the mixing chamber housing (7, 18) and enclosed by the mixing chamber housing (7, 18), the liquid medium housing enclosing the mixing chamber (21A, 21B), the liquid medium housing comprising an open second liquid medium housing side directed to the liquid medium injection port, said open second liquid medium housing side forming the entry for exhaust gases and liquid medium into the mixing chamber (21A, 21B), the liquid medium injection port and the liquid medium housing being arranged such that liquid medium is only injected into the liquid medium housing, wherein outer walls of the liquid medium housing are spaced from inner walls of the mixing chamber housing (7, 18), and wherein the exhaust gases inlet and the liquid medium housing are arranged such that, during operation, a flow of exhaust gases free of liquid medium is created around the liquid medium housing, wherein the exhaust gases inlet and the liquid medium housing are arranged such that, during operation, the flow of exhaust gases free of liquid medium created around the liquid medium housing is directed to the open second liquid medium housing side directed to the liquid medium injection port, characterized in that the arrangement further comprises a tubular diesel particle filter housing extending through a lower opening of the baffle plate, said lower opening forming the exhaust gases inlet, said tubular diesel particle filter housing having a diesel particle filter housing axis extending transverse to the baffle plate, the injection port axis of the liquid medium injection port being transverse to the diesel particle filter housing axis and in that the distance between liquid medium housing first and second end walls (29, 30) and the baffle plate and end cap, respectively, has a value between 3 and 8 mm or a value between 4 and 6 mm or a value of 5 mm. - a mixing chamber housing (7, 18) enclosing a mixing chamber (21A, 21B), said mixing chamber housing (7, 18) comprising an exhaust gases inlet for introducing exhaust gases into the mixing chamber (21A, 21B) and a mixture outlet for supplying a mixture of liquid medium and exhaust gases out of the mixing chamber (21A, 21B); the mixing chamber housing (7, 18) being formed by a top wall, an end cap and a baffle plate, wherein the exhaust gases inlet and the mixture outlet are provided in the baffle plate, i.e. the exhaust gases inlet and the mixture outlet are positioned at the same side of the mixing chamber housing (7, 18); - a liquid medium injection port for injecting liquid medium into the mixing chamber (21A, 21B); - a liquid medium housing positioned within the mixing chamber housing (7, 18) and enclosed by the mixing chamber housing (7, 18), the liquid medium housing enclosing the mixing chamber (21A, 21B), the liquid medium housing comprising an open second liquid medium housing side directed to the liquid medium injection port, said open second liquid medium housing side forming the entry for exhaust gases and liquid medium into the mixing chamber (21A, 21B), the liquid medium injection port and the liquid medium housing being arranged such that liquid medium is only injected into the liquid medium housing, wherein outer walls of the liquid medium housing are spaced from inner walls of the mixing chamber housing (7, 18), and wherein the exhaust gases inlet and the liquid medium housing are arranged such that, during operation, a flow of exhaust gases free of liquid medium is created around the liquid medium housing, wherein the exhaust gases inlet and the liquid medium housing are arranged such that, during operation, the flow of exhaust gases free of liquid medium created around the liquid medium housing is directed to the open second liquid medium housing side directed to the liquid medium injection port,