Mixing group for mixing two compounds to obtain a mixture, such as bone cement or an acrylic resin or a hydraulic cement, comprising: - a first component (2; 20; 200) having a substantially tubular body and delimiting a first housing zone of a first compound to be mixed, said first component (2; 20; 200) having a first end as well as a second end, - a second component (3; 30; 300) with substantially tubular body and delimiting a second housing zone, said second component (3; 30; 300) having a third end as well as a fourth end, said second component (3; 30; 300) being set to contain a second compound to be mixed or a vial for containing a second compound to be mixed, said first housing zone being in fluid communication with said second housing zone, so as to allow the passage of said second compound from said second housing zone to said first housing zone, said group comprising: at least one third component (8; 80; 800) with substantially tubular body arranged between said first end of said first component (2; 20) and said third end of said second component (3; 30) or surrounding said first end and said third end, said first component (2; 20; 200) and said third component (8; 80; 800) being slidable with respect to each other and said second component (3; 30; 300) and said third component (8; 80; 800) being slidable with respect to each other, as well as sealing means (9, 10; 90, 100; 900, 1000) between said first component (2; 20; 200) and said third component (8; 80; 800) as well as between said second component (3; 30; 300) and said third component (8; 80; 800), characterized in that said group comprises a mixing unit within said first housing zone, said mixing unit being provided with a stem, a mixing rotor or impeller supported at a first end of said stem and intended to be rotated in said first housing zone. - a first component (2; 20; 200) having a substantially tubular body and delimiting a first housing zone of a first compound to be mixed, said first component (2; 20; 200) having a first end as well as a second end, - a second component (3; 30; 300) with substantially tubular body and delimiting a second housing zone, said second component (3; 30; 300) having a third end as well as a fourth end, said second component (3; 30; 300) being set to contain a second compound to be mixed or a vial for containing a second compound to be mixed, said first housing zone being in fluid communication with said second housing zone, so as to allow the passage of said second compound from said second housing zone to said first housing zone, said group comprising: at least one third component (8; 80; 800) with substantially tubular body arranged between said first end of said first component (2; 20) and said third end of said second component (3; 30) or surrounding said first end and said third end, said first component (2; 20; 200) and said third component (8; 80; 800) being slidable with respect to each other and said second component (3; 30; 300) and said third component (8; 80; 800) being slidable with respect to each other, as well as sealing means (9, 10; 90, 100; 900, 1000) between said first component (2; 20; 200) and said third component (8; 80; 800) as well as between said second component (3; 30; 300) and said third component (8; 80; 800), characterized in that said group comprises a mixing unit within said first housing zone, said mixing unit being provided with a stem, a mixing rotor or impeller supported at a first end of said stem and intended to be rotated in said first housing zone. at least one third component (8; 80; 800) with substantially tubular body arranged between said first end of said first component (2; 20) and said third end of said second component (3; 30) or surrounding said first end and said third end, said first component (2; 20; 200) and said third component (8; 80; 800) being slidable with respect to each other and said second component (3; 30; 300) and said third component (8; 80; 800) being slidable with respect to each other, as well as sealing means (9, 10; 90, 100; 900, 1000) between said first component (2; 20; 200) and said third component (8; 80; 800) as well as between said second component (3; 30; 300) and said third component (8; 80; 800), characterized in that said group comprises a mixing unit within said first housing zone, said mixing unit being provided with a stem, a mixing rotor or impeller supported at a first end of said stem and intended to be rotated in said first housing zone.