Previous work has suggested that gilts housed in a crated environment, without bedding, are more physiologically stressed over the pre-parturient period as characterised by elevated cortisol levels (Lawrence et al, 1994) compared to those housed in a straw bedded pen. β-endorphin and Adrenocorticotropic Hormone (ACTH) are released concomitantly from the adenohypophysis (Guillemin et al, 1977) and have been shown to increase during parturition in humans (Fajardo et al, 1994), with ACTH being involved in the stress response, and β-endorphin possibly playing a role in an endogenous defence against the pain of parturition. This study aimed to demonstrate the pre-parturient changes in these plasma hormonal concentrations and activity levels in relation to two different farrowing environments.