Data comprise measurements of carcass condition (age, sex, length, mass and fat score), age (from stable isotope analysis of whiskers and Cementum aging of teeth) and rodenticide concentrations (bromadiolone, difenacoum, brodifacoum, flocoumafen and difethialone) in liver tissues for 68 polecats found dead in Great Britain between 2013 and 2016. All carcasses were stored frozen until necropsy examination at the National Museum of Scotland (with support from The Negaunee Foundation). Liver samples were frozen and transferred to the Centre for Ecology & Hydrology (CEH) for rodenticide analysis. Funding for the rodenticide analysis was provided by the People's Trust for Endangered Species and CEH. PhD funding from The Vincent Wildlife Trust and the University of Exeter. Full details about this dataset can be found at https://doi.org/10.5285/2f49911c-192c-4f09-a1a2-72a21f20706c
