We have obtained single-phase compounds Gd ₃ Fe _29-x-y Co _x Cr _y with the Nd ₃ ( Fe,Ti )₂₉ -type. Cr is a stabilizing element and also increases the solid-solution limit of Co in the Gd ₃ Fe _29-x-y Co _x Cr _y compounds. Substitution of Co by Fe results in a significant change of the magnetocrystalline anisotropy and changes the easy magnetization direction from basal-plane to easy-axis when x≫10 and y=4. The intensity of the magnetic interactions in Co-rich Gd ₃ Fe _29-x-y Co _x Cr _y compounds has been calculated from the high-field magnetization measurements. The Co substitution suppresses the Invar anomaly found in the Gd ₃( FeCr )₂₉ compounds. © 2003 American Institute of Physics.