In Australia an alternative procedure for collecting pregnant mare urine (PMU) has been developed. The Australian systems allows the mares to be loose housed in stables or outdoors, where as the current system in Canada and North Dakota requires that the mares be tethered in stalls. The welfare risks associated with this alternate procedure were examined in this study. Twenty-four pregnant mares ranging from three to five months of gestation were used in this study. Twelve of the mares were fitted with the PMU collection device housed in a group on a large paddock during the day. Twelve control mares were housed on a separate paddock. In the evening, the mares were kept in groups of four in six small enclosures. The mares on the experimental treatment continued to where the PMU collection device throughout the evening. There was very little or no difference in the behaviour of the control mares and those fitted with a PMU collection device. The day the mares were fitted with the device, they were observed to frequently lift their leg in the direction of the collection device, however this behaviour subsided the following day. The behaviour patterns of the mares on the two treatments remained similar throughout gestation, except in for the lying behaviour. Mares fitted with a PMU collection device spent significantly less time lying during the evening, as fewer mares were observed to lie down. It remains to be determined how the changes in the lying behaviour affect the welfare of the mares. As the lying behaviour of the mares remained the same after the PMU collection device was removed. The heart rate and cortisol concentrations taken the first two days after the PMU collection device was attached do not indicate that the mares underwent an acute stress response to the attachment of the device. Six to seven weeks after the device was attached, the cortisol concentrations were not indicative of stress. The adrenal cortex did not demonstrate an increased sensitivity of an ACTH challenge six weeks after the mares were fitted with the PMU collection device. The data establishes that mares that wear a PMU collection device 5 days per week for seven weeks, do not undergo an impairment in their welfare.