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 (RZ1) of a first compound to be mixed, the first component (2； 20； 200) having a first end (2a) as well as a second end (2b), a second component (3； 30； 300) with substantially tubular body and delimiting a second housing zone (RZ2), the second component (3； 30； 300) having a third end (3a) as well as a fourth end (3b), the 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, the first housing zone (RZ1) being in fluid communication with the second housing zone (RZ2), so as to allow the passage of the second compound from the second housing zone (RZ2) to the first housing zone (RZ1), wherein the group comprises: at least one third component (8； 80； 800) with substantially tubular body arranged between the first end (2a) of the first component (2； 20) and the third end (3 a) of the second component (3； 30) or enclosing the first end (2a) and the third end (3a), the first component (2； 20； 200) and the third component (8； 80； 800) being slidable with respect to each other and the second component (3； 30； 300) and the third component (8； 80； 800) being slidable with respect to each other, as well as sealing means (9, 10； 90, 100； 900, 1000) between the first component (2； 20； 200) and the third component (8； 80； 800) and between the second component (3； 30； 300) and the third component (8； 80； 800).
