This paper describes improvement of the strength of sintered products made from cast iron powder in combination with dimensional precision. Various mixtures consisting of cast iron powder, reduced iron powder, and partially pre-alloyed copper-iron powder were compacted at 800 MPa and sintered at 1423 K for 0.5-20 h in hydrogen atmosphere. The results shows that the tensile strength of 890 MPa can be achieved by the sintering of cast iron powder mixed with iron powder. It is also shown that by substituting partially pre-alloyed copper-iron powder for normal reduced iron powder, dimensional precision can be controlled. Consequently, at a given strength level, it is possible to achieve considerable saving of expensive alloying elements by using cast iron powder.