Please cite this article as: Cánovas, M., Mentaberre, G., Tvarijonaviciute, A., Casas-díaz, E., Navarro-gonzález, N., Lavín, S., Soriguer, R.C., González-candela, M., Serrano, E.,Fluctuating asymmetry as a proxy for oxidative stress in wild boar, Mammalian Biology (2015), http://dx.doi.org/10.1016/j.mambio. 2015.03.004 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The study of fluctuating asymmetry (FA) in living organisms has produced contradictory results over 22 the past few decades of research. Though the protocol for measuring FA is firmly established, the 23 sources of FA remain unclear in many cases. Our goal is to examine the relationship between FA 24 and both the concentration of biomarkers of reactive oxygen species (ROS) and body condition in a 25 medium-sized mammal, the European wild boar (Sus scrofa). Using a Partial Least Squares 26 regression (PLSr), we found a positive significant relationship (Stone-Geisser test) between 27 oxidative stress and FA but a negative relationship between oxidative stress and body condition. Our 28 results suggest that FA can be used to assess the physiological costs associated with oxidative 29 stress in mammals. 30