Abstract
The thesis analyses how institutional complexity manifests itself and transforms in contemporary healthcare systems. Through three qualitative studies and three metaphors, it investigates different forms of institutional dynamism: in oncology departments, authority shifts (boat) from epistemic to managerial, redefining hierarchies and roles; the introduction of generative artificial intelligence leads to internal fractures (arena) within the managerial logic itself, showing how technological innovation can catalyse interpretative tensions between managers; in rural primary care, professional autonomy emerges as a product of institutional infrastructures (cage). The thesis proposes a dynamic theory of institutional complexity, depicted through three metaphors, offering a coherent interpretative framework: institutional complexity is a dynamic and multifaceted phenomenon; professionals do not merely suffer it but interpret and produce it through their daily work, with significant implications for healthcare governance.