Foxes concentrate their activities around den sites during the breeding period and regularly visit dens at other times of the year, meaning den location is an important consideration in efforts to control foxes and protect native prey species. We investigated factors that influence den-site selection by foxes to improve information on potential interactions with prey species, and assess the usefulness of targeting den sites for fox control. We measured 76 earthen and non-earthen fox dens on farmland in south-eastern Australia and compared these with paired random sites in relation to vegetation/land-use type, soil clay content, and proximity to landscape features (tree, water, fence and road). Most dens were earthen and primarily located in open farmland, whereas non-earthen dens were mostly found in roadsides. The proportion of non-earthen dens located by landholders (7.8% of 51 dens) was substantially lower than the proportion of non-earthen dens identified with radio-tracking (77.8% of 18 dens). The average clay content at earthen dens was significantly lower than that at non-earthen dens (t' = '5.192, P < 0.001) and random sites (t' = '5.196, P < 0.001). Soil texture was a key factor influencing fox den location, and this information should greatly improve fox control in agricultural landscapes for the benefit of native and non-native prey.