In the course of the spring 1984, the authors visited about 200 fox dens in the southern and eastern parts of the Province de Liège (eastern Belgium). Each den site was described. Then a multivariate analysis (reciprocal averaging) was performed to identify, when possible, the parameter(s) influencing the fox habitat choice. Fox dens generally are built in forested habitats with no or only a poor scrub layer and are southernly or westernly oriented. For what concerns the other habitat parameters, the fox appears to be very opportunistic. For example, in the vicinity of roads or human dwellings, his den will be established under a dense vegetation cover whereas in the middle of forested areas it has to be found in open wood or near clearcuts. In our study area, fox dens with more than 5 main entrances are not common. Frequently they are not occupied for more than one reproduction season. Cohabitation with badger was noted in 15 cases (59 fox occupied dens) and with rabbit in 4 cases only.