SUMMARY This pilot study tried to answer the question however the present animal welfare regulations for horses regarding lying hall area requirements are adequate for horses older than 24 months. The study was carried out at one of the largest stud farms for standard bred horses in Sweden. Mares in late pregnancy with an initial mean age of 10 years was used in a behaviour study. The influence of varying space per animal in a loose-housing system on behaviours like the horses' lying hall use, standing, resting, moving behaviour and threats was studied. The behaviour at three different horse densities ? 18 mares, 13 mares and 8 mares (7.4 m2, 10.3 m2 and 16.7 m2 per mare, respectively) ? was recorded by use of video.