This publication combines two topics of interest in the form of a case study: Private Banking and Behavioural Finance. Private Banking is increasingly interesting from the banks' and the customers' viewpoint as on the one hand, the bank has a high potential margin in this field and on the other hand, the number of high net worth individuals (HNWI) as a potential customer base is steadily increasing. Furthermore, as Private Banking is a people's business, understanding customers holistically is a vital point to ensure a satisfying consulting quality and subsequent business relationship. The knowledge of Behavioural Finance aims to achieve the goal of a better comprehension of Private Banking clients and their respective thinking patterns and its concepts are developed to avoid making common psychological mistakes when it comes to investing and taking financial decisions. Thus, combining Private Banking and Behavioural Finance has a great potential which is explored in this publication.