An axially elongate mixing chamber defined by a mixer housing has a cylindrical sidewall and concave inwardly open hemispherical inlet and outlet end walls which form contiguous juncture with associated ends of the sidewall. A plurality of pressurized fluent materials to be mixed enter the mixing chamber from a manifold and through a common inlet passageway which terminates at a nozzle coaxially positioned within a cylindrical portion of the mixer housing. A plurality of equiangularlly spaced discharge passageways in the nozzle which terminate at discharge orifices redirect the material toward the juncture formed by the cylindrical sidewall and the hemispherical inlet end wall. A coaxial outlet orifice opens through the outlet end wall and has a cross sectional area greater than the total cross sectional area of the discharge orifices whereby a pressure drop occurs across the nozzle resulting in acceleration of the fluent material discharged from the nozzle and generally toward a turbulent mixing zone located between the nozzle and the inlet end wall. Further mixing occurs as the material moves from the mixing zone through the cylindrical portion of the chamber to the outlet end and through the outlet orifice.