International Journal of Production Economics, v. 233. Abstract: The purpose of this research is to use a paradox theory lens to investigate in greater depth how to manage cultural tensions in a healthcare organisation implementing lean. Conducting an in-depth single case study at a private specialized hospital, we classify cultural tensions according to the four categories proposed by paradox theory – namely learning, organizing, belonging and performing. Our study scrutinizes the role of the dimensions of organisational culture (OC) as antecedents to both defensive mechanisms (i.e. resistance to change) and managerial actions (lean practices). From a theoretical perspective, this research offers key implications. We expose a nuanced view of how different OC traits may act as either drivers or barriers to lean implementation. In addition, we show how lean practices act as managerial actions that can help mitigating defensive mechanisms and thus help managing the four types of paradoxes. We also offer a specific discussion of the paradox of learning, previously missing in prior studies of lean. From a managerial perspective, the study offers a guide to managers dealing with cultural resistance that naturally emerges during lean implementations. To the best of our knowledge, no previous study has explored the interplay of lean implementation and OC using a paradox theory lens.