The terbium-iron phase diagram has been determined using metallographic, X-ray diffraction, differential thermal analysis, and electron microprobe techniques. The terminal solubilities of the two elements are extremely restricted, of the order of 0.1 at.% for Tb in Fe. A eutectic reaction takes place at 28 at.% Fe, 847 °C. The four intermetallic compounds, TbFe 2, TbFe 3, Tb 6Fe 23, and Tb 2Fe 17 melt non-congruently at 1187, 1212, 1276, and 1312 °C, respectively. The Tb 2Fe 17 compound appears in the rhombohedral Th 2Zn 17 modification on the Tb-rich side and in the hexagonal Th 2Ni 17 modification on the Fe-rich side of the stoichiometric composition.