The effects of density on displacements, falls, injuries, and orientation among horses being transported in a single-deck, open-topped semi-trailer were evaluated. Horses were either transported at high density (1.28 m2 / horse with 14 horses) or low density (2.23 m2 / horse with eight horses). The horses were transported for two laps on a course, which was 7.28 km and took approximately 25 min to complete. There were two 60 turns, four 90 turns, two 120 turns, one 180 turn, six hard breaks, and six rapid accelerations on each lap. The behaviour of the horses was videotaped using overhead video cameras. The number of displacements did not differ between the two densities. More horses fell in the high density treatment than the low density treatment. More horses were injured in the high density treatment than in the low density treatment. However, the severity of injuries did not differ between the two treatments. The horses did not seem to have a preferred orientation during travel, as there were no differences between those facing forward and those facing away from the direction of travel. Transporting horses at high stocking densities results in a higher incidence of falls and injuries, and can make it more difficult for the horse to get up after a fall.