While there has been substantial research conducted in the business to consumer (B2C) sector on brand loyalty, there is scant evidence of the same in the business to business (B2B) sector (Russell-Bennett, McColl-Kennedy, & Coote, 2007). This paper seeks to advance the understanding of business brand loyalty through the use of a tri-dimensional approach to brand loyalty and the identification of the psychological function that these dimensions of brand loyalty provide to the business buyer. The four functions of utilitarian, knowledge, value-expression and ego-defence provide insight into the benefits that are gained by the business buyer from being loyal. Mail surveys were completed by 105 Australian businesses. The relationship between the functions and three dimensions of loyalty were examined using correlation analysis. The results show that all four functions of brand loyalty were identified as benefits by different business buyers and there were different relationships between these functions and each of the three dimensions of brand loyalty. Importantly, the role of emotions in business buying has been highlighted as an area needing further investigation.