The purpose of this study was to evaluate active stable systems, and their improvement of the horses on animal welfare and the horses’, natural behavior. The evaluation was made through interviews with the managers of two active stables in Piteå, Sweden and practical studies of the horses’ behavior at those two active stables and also one traditional stable. The results showed that the horse’s circadian rhythm differed between the various groups. The horses that were kept in the active stable systems rested and foraged spread over day and night while horses kept in the traditional stable mainly rested at night and ate during the day. The horses get better outlet for their natural behavior in the active stable system because the need of movement and socializing were met around the clock. Keeping horses in the active stable system, however, is associated with a risk of injury because of the competitive situations that occur around the feeding stations, and trauma injuries have occurred in both active stables in this study.