This paper offers a detailed investigation of the LXX texts underlying the seven OT citations in Hebrews chapter 1, taking account of significant twentieth-century manuscript discoveries and recent developments in the field of Septuagintal Studies. The findings are then related to the study of the use of the OT in the NT more generally, and to some important current issues in the study of the LXX, such as the value of Lucianic readings. This investigation supports the growing consensus that the author of Hebrews reproduced his scriptural citations faithfully, so that the burden of proof should now rest with those who argue for a deliberate alteration of his source.