Some studies focused on food purchase by low-income consumers have been published in the last years (Grossi, Motta e Hor-Meyll, 2008; Parente, Barki and Kato, 2005). However, these studies were based in data collected after the purchase and provided by consumers. This exploratory study aimed to increase understanding of low-income consumers behavior at the point of sale. Initially, consumer routes and behaviors in four supermarkets located in low-income areas in Rio de Janeiro were observed and noted. Then, those consumers whose purchase paths had been observed answered questions about shopping list formulation, behavior in store, decisions made in store, hesitation in making some choices. The results show that, beside the fact that income constraint played an important role in food purchasing, other factors help to understand decision making in supermarkets by low-income consumers. From observation and interviews emerged influences related to store environment, to how available brands are perceived and to the risk perceived by consumers at the bottom of the economic pyramid.