Exhaust treatment system, arranged for treatment of an exhaust stream, which results from a combustion in a combustion engine, characterised by - a first oxidation catalyst, arranged to oxidise compounds comprising one or several of nitrogen, carbon and hydrogen in said exhaust stream; - a first dosage device, arranged downstream of said first oxidation catalyst, and arranged to supply a first additive into said exhaust stream; - a first reduction catalyst device, arranged downstream of said first dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive, wherein said first reduction catalyst device comprises at least one multifunctional slip-catalyst, said at least one multifunctional slip catalyst including: - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; said at least one multifunctional slip catalyst thereby being arranged primarily for reduction of nitrogen oxides NO x, and secondarily for oxidation of additive in said exhaust stream; - a second oxidation catalyst, which is arranged downstream of said first reduction catalyst device, and is arranged to oxidise one or several of nitrogen oxide NO and incompletely oxidised carbon compounds in said exhaust stream; - a particulate filter, which is arranged downstream of said second oxidation catalyst, and is arranged to catch and oxidise soot particles; - a second dosage device, arranged downstream of said particulate filter, and arranged to supply a second additive into said exhaust stream; and - a second reduction catalyst device, arranged downstream of said second dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least one of said first and said second additives. - a first oxidation catalyst, arranged to oxidise compounds comprising one or several of nitrogen, carbon and hydrogen in said exhaust stream; - a first dosage device, arranged downstream of said first oxidation catalyst, and arranged to supply a first additive into said exhaust stream; - a first reduction catalyst device, arranged downstream of said first dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of said first additive, wherein said first reduction catalyst device comprises at least one multifunctional slip-catalyst, said at least one multifunctional slip catalyst including: - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; - a nitrogen oxides NO x reducing coating being in direct contact with the exhaust stream that passes through the exhaust treatment system; and - one or several substances comprised in platinum group metals, and/or one or several other substances that provide similar characteristics as for the platinum group metals; - a second oxidation catalyst, which is arranged downstream of said first reduction catalyst device, and is arranged to oxidise one or several of nitrogen oxide NO and incompletely oxidised carbon compounds in said exhaust stream; - a particulate filter, which is arranged downstream of said second oxidation catalyst, and is arranged to catch and oxidise soot particles; - a second dosage device, arranged downstream of said particulate filter, and arranged to supply a second additive into said exhaust stream; and - a second reduction catalyst device, arranged downstream of said second dosage device, and arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least one of said first and said second additives.