This is the uncorrected proof of the following paper:García-Vázquez, A., Pinto-Llona, A.C. & Grandal-d’Anglade, A. (2018). Brown bear (Ursus arctos L.) palaeoecology and diet in the Late Pleistocene and Holocene of the NW of the Iberian Peninsula: A study on stable isotopes. Quaternary International. 481, 42 - 51. DOI: 10.1016/j.quaint.2017.08.063 This work was part of the PhD thesis of AGV and was carried out under the Research Project BIOGEOS, founded by MINECO/FEDER (CGL2014-57209-P) and a Consolidating Grant from the Xunta de Galicia for emerging research groups (GPC2015/024). Authors thanks the speleologists involved in cave prospections, especially Dr Marcos Vaqueiro, the Federación Galega de Espeleoloxía and the Federación Asturiana de Espeleología; Dr. Juan Francisco García Marín and Mr. Victor Vázquez Fernádez, for supply of supply of modern samples and Dr. Carlos Fernández Rodríguez for A Braña-Arintero samples. The authors thank two anonymous reviewers that contributed to improve the previous version of the manuscript with valuable comments.