The most common housing system within the European Union for gestating sows and gilts have for many years been individual stalls while Sweden on the contrary has a long history, since the end of the 1980s, of group housing. The switch of breeding material in the beginning of the 2000ies in Sweden resulted in the end of breeding of the Swedish Yorkshire (SY), and instead the Dutch Yorkshire (ZY) was introduced to Swedish pig producers. Because the genetic selection of these two lines of York-shire pigs have been performed in different environments, this may have cause be-havioural differences between them that may be important in group housing systems. The overall aims of this MSc thesis study was to develop relevant protocols that could be used to record health and behaviour in pigs, but also to investigate if there are any differences in health and behaviour between the two line crosses of pigs in three dif-ferent age categories; sows (N=16), piglets (N=38) and slaughter pigs (N=40) where piglets and slaughter pigs had Hampshire (H) as sire breed. The health and behaviour were recorded through direct observation on each individual focal animal. Scan sam-pling was used to record different variables of body posture, location in the pen and activity. Social interactions that involved the focal animals were observed continu-ously for five minutes for each pen. Lameness, locomotion and wounds on the body were investigated and recorded as measurements of health in the health assessment. In general, the results showed that there were relatively few differences in behav-iour and health between the different line crosses in the three different age categories. However, it was found in the health assessment that SY sows had significantly more wounds on the ears compared to ZY sows (P=0.016) and SY*H slaughter pigs had more wounds on the middle part of the body than ZY*H slaughter pigs (P=<0.0001). There was also a tendency (P=0.062) that ZY*H piglets had more wounds on the hindquarters compared to SY*H piglets. The ...