When farm animals are transported over long distances there is concern about their welfare. This has resulted in consumer pressure and additional legislation to control the transport of animals. However, information on the behavioural and physiological responses of sheep to transport is required to assess which aspects of transport can cause welfare problems. An optimal space allowance for long distance transport of sheep should ideally provide stability; allow normal posture (during standing and lying), and postural adjustments, without causing an increased risk of injury and psychological ‘stress’. Direct behavioural observations of potentially traumatic events related to vehicle movement and behavioural interactions (riding and trampling) were recorded during transport. Postures, orientation, rumination and eating were recorded to determine whether there was sufficient space to lie down during transport and to assess the relative priorities for resting and eating post-transport. Measurements of ‘stress’ (heart rate and plasma concentrations of Cortisol); injury (plasma activities of creatinine kinase and aspartate aminotransferase, and acceleration sensors), and dehydration (packed cell volume, plasma osmolality, plasma concentrations of total protein, vasopressin and sodium, water intake and live-weight change) were also made.