Animals often co-exist with humans inside buildings, however in birds such cases are only sporadically noted. In this paper we describe the occurrence of House Sparrows in supermarket interiors. The probability of House Sparrows presence was higher in larger markets and during winter period. The abundance and density of birds were positively and negatively related to the size of the supermarket, respectively. The birds were active at night. They foraged mainly along market shelves on bakery products, vegetables and cereals. We did not observe nesting inside market halls. The supermarkets seem to be hospitable wintering place for this species, however they may also be ecological traps imprisoning the birds once they find their way in. Moreover, House Sparrows may contaminate food, thus, the presence of such species inside supermarkets should be controlled.