Abstract: A rotary piston machine includes a piston arrangement mounted in a gas-tight interior housing, wherein the piston arrangement has at least four individual rotary pistons which are constructed essentially equally and have end faces which are arranged so as to be in alignment with each other. The rotary piston machine further includes sealing assemblies composed of positioning members and sealing rods, wherein a sealing assembly is provided for each gap between adjacent rotary pistons and wherein each sealing assembly includes at least one sealing rod. The center points of circular arcs with two different radii defining the cross-section of each rotary piston are located on the corner points of a rhombus and the center points of the larger circular arcs are located in the corner points with the larger rhombus angles, wherein the larger rhombus angle is greater by 50.degree. to 50.degree. than the smaller rhombus angle.