A systematic study on the ternary uranium-iron-antimony was made at 700 and 750 degrees C through powder X-ray diffraction and Scanning Electron Microscopy, coupled with Energy Dispersive Spectrometry. The assessed sections confirmed the existence and crystal structure of the binary intermetallic compounds stable at these temperatures, as well as the UFeSb(2)ternary phase. Moreover it was found that UFeSb2 is part of a solid solution, UFe1-xSb2, stable for 19<Fe<24 at.% at 700 degrees C and 16<Fe<25 at.% at 750 degrees C. A new ternary phase, U3Fe3-xSb4, crystallizing in the cubic type Y3Au3Sb4 and stable for 22<Fe<33 at.% at 700 degrees C, and 14<Fe<33 at.% at 750 degrees C was also revealed in the present work.