A hydraulic assembly, in particular for braking systems and/or for actuating clutches, comprising: - a hydraulic unit having a hydraulic unit body, in which at least one delivery channel is obtained, wherein said hydraulic unit body comprises a hydraulic unit body base, in which an inlet mouth of said delivery channel is obtained; said hydraulic assembly further comprises at least one connection comprising: - a feed pipe adapted to receive an entering hydraulic fluid, and - an eyelet adapted to output said fluid, said eyelet delimiting an eyelet hole defining an eyelet axis (X-X) which defines an axial direction (A-A), a radial direction (R-R) perpendicular to said axial direction (A-A), and a circumferential direction (C-C) transversal to said axial direction (A-A) and to said radial direction (R-R), wherein said eyelet comprises an upper eyelet sealing surface and a lower eyelet sealing surface; said hydraulic assembly further comprising: - at least one pipe union having a hollow cylindrical body and a pipe union head, wherein said hollow cylindrical body is configured to receive said fluid from said eyelet and to introduce said fluid into said delivery channel, wherein said pipe union is arranged coaxially to said eyelet hole, - at least one upper gasket arranged between said upper eyelet sealing surface and said pipe union head, - at least one lower gasket arranged between said lower eyelet sealing surface and said hydraulic unit body base; wherein said connection comprises at least one shoulder which extends sideways, at least in a radial direction (R-R), to said eyelet, wherein said shoulder comprises a lower projection which extends in an axial direction (A-A) by the side of said lower eyelet sealing surface, so as not to interfere with said lower gasket; characterized in that said hydraulic unit body base comprises a cavity configured to accommodate said lower projection in a complementary manner, so that, by virtue of the shape and to the mechanical interaction between the cavity and the lower projection and J as soon as said lower projection and said cavity are coupled to each other, said at least one connection is coupled in a fail-proof manner to said hydraulic unit, thus preventing it from rotating in a circumferential direction (C-C) both during assembly and during use. - a hydraulic unit having a hydraulic unit body, in which at least one delivery channel is obtained, wherein said hydraulic unit body comprises a hydraulic unit body base, in which an inlet mouth of said delivery channel is obtained; said hydraulic assembly further comprises at least one connection comprising: - a feed pipe adapted to receive an entering hydraulic fluid, and - an eyelet adapted to output said fluid, said eyelet delimiting an eyelet hole defining an eyelet axis (X-X) which defines an axial direction (A-A), a radial direction (R-R) perpendicular to said axial direction (A-A), and a circumferential direction (C-C) transversal to said axial direction (A-A) and to said radial direction (R-R), wherein said eyelet comprises an upper eyelet sealing surface and a lower eyelet sealing surface; - a feed pipe adapted to receive an entering hydraulic fluid, and - an eyelet adapted to output said fluid, said eyelet delimiting an eyelet hole defining an eyelet axis (X-X) which defines an axial direction (A-A), a radial direction (R-R) perpendicular to said axial direction (A-A), and a circumferential direction (C-C) transversal to said axial direction (A-A) and to said radial direction (R-R), wherein said eyelet comprises an upper eyelet sealing surface and a lower eyelet sealing surface; said hydraulic assembly further comprising: - at least one pipe union having a hollow cylindrical body and a pipe union head, wherein said hollow cylindrical body is configured to receive said fluid from said eyelet and to introduce said fluid into said delivery channel, wherein said pipe union is arranged coaxially to said eyelet hole, - at least one upper gasket arranged between said upper eyelet sealing surface and said pipe union head, - at least one lower gasket arranged between said lower eyelet sealing surface and said hydraulic unit body base; - at least one pipe union having a hollow cylindrical body and a pipe union head, wherein said hollow cylindrical body is configured to receive said fluid from said eyelet and to introduce said fluid into said delivery channel, wherein said pipe union is arranged coaxially to said eyelet hole, - at least one upper gasket arranged between said upper eyelet sealing surface and said pipe union head, - at least one lower gasket arranged between said lower eyelet sealing surface and said hydraulic unit body base; wherein said connection comprises at least one shoulder which extends sideways, at least in a radial direction (R-R), to said eyelet, wherein said shoulder comprises a lower projection which extends in an axial direction (A-A) by the side of said lower eyelet sealing surface, so as not to interfere with said lower gasket; characterized in that said hydraulic unit body base comprises a cavity configured to accommodate said lower projection in a complementary manner, so that, by virtue of the shape and to the mechanical interaction between the cavity and the lower projection and J as soon as said lower projection and said cavity are coupled to each other, said at least one connection is coupled in a fail-proof manner to said hydraulic unit, thus preventing it from rotating in a circumferential direction (C-C) both during assembly and during use.