||The aim of this study was to establish some basic facts about weanling horse (Equus caballus) behaviour in a loose housing/paddock environment during winter. The behaviour of 10 foals (seven American Standardbred and three Finnish cold-blooded foals) was observed in a cold loose housing/paddock environment from December 2002 to March 2003. The time budget, circadian rhythm and effect of weather conditions on behaviour were examined. The foals were observed for a total of 23 24-h periods by video recording. The method used was instantaneous sampling (), where the locations of foals were noted at every 15 min along with the behaviour performed at that time. Temperature, humidity and wind speed were recorded three times a day. The foals spent 43.2 +/- 6.6% of the time in the sleeping hall (an insulated building with a deep-litter bed), 51.4 +/- 5.8% in the open paddock and 5.2 +/- 2.7% in the shelter (a two-sided, roofed entrance shelter in front of the sleeping hall). The time spent outdoors was greatest between the hours of 08:00 and 20:00, but the foals spent some time outdoors also at night. They spent most of the day eating hay (27.6 +/- 3.0%) (offered ad libitum), standing (25.5 +/- 2.8%) and resting (32.1 +/- 2.4%). The proportion of locomotive behaviour patterns was 5% of the observations. The foals in this study were able to perform species-specific behaviour patterns (resting, eating, being active) and to follow the natural circadian rhythm of these patterns. The behaviour of the foals did not change much as the temperature dropped from 0 to -20 [degree sign]C. The time spent in the sleeping hall did not increase greatly, nor the time spent eating, resting or lying close to each other (huddling). On the basis of their behaviour, the weanling horses did not seem to suffer from the cold environment.