ABSTRACT. The objective of this work is to characterize two contrasting systems of fattening pigs in Uruguay. A total of 96 pigs (average 41.7 kg) were divided into eight groups of 12 animals, representing two production systems:(IN) pigs confined in pens of 12 m2 or (OUT) kept in plots with field shelters and access to pasture. Behavioral observations were performed by scan sampling at 5-minute intervals, three times a day during weeks 6, 8, 10 and 12 of the experiment. Aggressions were also observed at the end of the experimental period. Blood samples were taken for cortisol analysis and other physiological parameters, during growth period and slaughter and meat quality characteristics were assessed after slaughter. Differences were found in carcass characteristics, wherein IN presented a higher dorsal fat. These animals presented an overall lower activity and spent less time resting, with a stable pattern throughout the day. In OUT, pigs usually rested at midday hours, more active in the morning and afternoon. The number of total reciprocal aggressions in the observation period was 4.2±3.7 for IN and 2.3±2.2 for OUT. Cortisol levels and biochemical profile did not show evidence of important problems in the animals. Welfare is not compromised in any of the systems, although higher levels of cortisol and aggressions could be indicating some stress problems in the confinement system. Meat characteristics in OUT were considered better than in IN from a nutritional point of view.