A process for producing multimodal ethylene polymers in the presence of a polymerization catalyst comprising the steps of: - polymerizing ethylene in a first polymerization stage at a temperature of from 30 to 70 °C, preferably from 40 to 60 °C and a pressure of from 1 to 150 bar, preferably from 10 to 100 bar, in the presence of the polymerization catalyst to produce a first homo- or copolymer of ethylene; - polymerizing ethylene in a second polymerization stage at a temperature of from 50 to 115 °C, preferably from 90 to 105 °C, and a pressure of from 1 to 150 bar, preferably from 50 to 100 bar in the presence of hydrogen and the first homo- or copolymer of ethylene to produce a first ethylene polymer mixture comprising the first homo- or copolymer of ethylene and a second homopolymer of ethylene; - copolymerizing ethylene in a third polymerization stage at a temperature of from 50 to 100 °C, preferably from 65 to 90 °C, and a pressure of from 10 to 40 bar, preferably from 15 to 30 bar, in the presence of an alpha-olefin comonomer having from 4 to 10 carbon atoms and the first ethylene polymer mixture to produce a second ethylene polymer mixture comprising the first ethylene polymer mixture and a third copolymer of ethylene; wherein the first homo- or copolymer of ethylene has a melt flow rate MFR 21 of not more than 1.0 g/10 min; the first ethylene polymer mixture has a melt flow rate MFR 2 of from 10 to 250 g/10 min and a density of higher than 965 kg/m 3; and the second ethylene polymer mixture has a melt flow rate MFR 21 of from 1 to 50 g/10 min and a density of from 935 to 960 kg/m 3 and wherein the first ethylene polymer mixture comprises from 2 to 20 % by weight of the first homo- or copolymer of ethylene and 80 to 98 % by weight of the second homopolymer of ethylene, and wherein the second ethylene polymer mixture comprises from 40 to 60 % by weight of the first ethylene polymer mixture and from 40 to 60 % by weight of the third copolymer of ethylene. - polymerizing ethylene in a first polymerization stage at a temperature of from 30 to 70 °C, preferably from 40 to 60 °C and a pressure of from 1 to 150 bar, preferably from 10 to 100 bar, in the presence of the polymerization catalyst to produce a first homo- or copolymer of ethylene; - polymerizing ethylene in a second polymerization stage at a temperature of from 50 to 115 °C, preferably from 90 to 105 °C, and a pressure of from 1 to 150 bar, preferably from 50 to 100 bar in the presence of hydrogen and the first homo- or copolymer of ethylene to produce a first ethylene polymer mixture comprising the first homo- or copolymer of ethylene and a second homopolymer of ethylene; - copolymerizing ethylene in a third polymerization stage at a temperature of from 50 to 100 °C, preferably from 65 to 90 °C, and a pressure of from 10 to 40 bar, preferably from 15 to 30 bar, in the presence of an alpha-olefin comonomer having from 4 to 10 carbon atoms and the first ethylene polymer mixture to produce a second ethylene polymer mixture comprising the first ethylene polymer mixture and a third copolymer of ethylene; wherein the first homo- or copolymer of ethylene has a melt flow rate MFR 21 of not more than 1.0 g/10 min; the first ethylene polymer mixture has a melt flow rate MFR 2 of from 10 to 250 g/10 min and a density of higher than 965 kg/m 3; and the second ethylene polymer mixture has a melt flow rate MFR 21 of from 1 to 50 g/10 min and a density of from 935 to 960 kg/m 3 and wherein the first ethylene polymer mixture comprises from 2 to 20 % by weight of the first homo- or copolymer of ethylene and 80 to 98 % by weight of the second homopolymer of ethylene, and wherein the second ethylene polymer mixture comprises from 40 to 60 % by weight of the first ethylene polymer mixture and from 40 to 60 % by weight of the third copolymer of ethylene.