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In the present research three experiments were carried out to evaluate the effects of thermal conditions of season (winter or summer) on feed intake of growing-finishing pigs reared in Alentejo zone in buildings with low environmental control (experiment 1), to examine possible interactions with animal density (experiment 2) and with diet energy density (experiment 3). A total of 480 crossbred pigs (Duroc Jersey, Landrace, Large White and Pietrain) of both sexes (entire males and females) were used. The thermal conditions of the Alentejo region are commonly extreme in winter and summer, being largely outside of the optimal temperature range (20C to 25C) for growingfinishing pig performance. In the three experiments, the major part of time, animals were subject to temperatures below lower critical temperature, during winter and many times higher than upper critical temperature, during summer. Results of experiment 1 indicated that pigs raised during winter consumed more feed (p<0,001) than during summer. In winter daily feed intake increases linearly with liveweight increase. However in summer this relationship was curvilinear. In both seasons, the increase of animal density from 1.50m2.pig-1 to 0.75m2.pig-1 (experiment 2) resulted in a similar decrease (p <0.001) in feed intake. During summer pigs consumed more feed (p<0.001) during the night period compared with the day period. Pigs on the low energy diet (experiment 3) recorded a higher feed consumption (p<0.05) than pigs on high energy diet but there was not significant (p<0.005) difference in energy intake. Overall, results of the three experiments evidenced the major importance of environmental temperature on growing-finishing pig feed intake. They also demonstrate that strategies related to the handling of animals could help to alleviate the thermal effects.