Public concern about animal welfare has increased both legislation and consumer pressure, to introduce new technical developments in sow’s housing. In recent years, there has been increased interest in less intensive production systems for pigs, including outdoor production. The issue of sow’s housing and its relation to welfare has been investigated for sometime now (SVC, 1997; McGlone et al., 2004). Concerns over animal welfare combined with European based scientific data have led to the progressive removal of gestation stalls in several European countries, and from 2013 the use of stalls will be restricted throughout the European Union. Therefore one of the greatest challenges in swine housing management is the development of a viable alternative to stalls. In this way, we carried out a study to (1) compare the agonistic behaviour of two breeds of sows moved from individual stalls to an outdoor park, and to (2) determine the evolution of behaviour throughout four weeks of study for each breed.