Studies concerning farm animals are increasingly using heart rate (HR) as a welfare indicator because it is thought to be affected during the situations which an animal perceives as ‘stressful’. However, many studies are based on insufficient fundamental information and a limited understanding of the methodology. It has been established that an animal can respond to short-term ‘stressful’situations by rapidly releasing adrenaline which increases heart rate, heart output and blood pressure, and potentially prepares an animal for the ‘fight or flight’ response. However, it is self evident that heart rate is also affected by factors other than the release of adrenaline. Indeed, other studies and reviews (Baldock and Sibly, 1990 ; Fraser and Broom, 1990) have commented on the need to remove, primarily, behaviour as a confounding variable in studies using heart rate as a welfare indicator. Therefore, it is essential that the correct protocol is followed if heart rate is to be used as an unconfounded, objective indicator of welfare. Thus, the aim of the following study was to observe the effect of specific environmental occurrences on the HR of dairy cattle during the milking process, whilst illustrating a method of extracting heart rate data which could be used as a welfare indicator.