Paget’s disease of bone is a chronic metabolic bone disease due to disturbance in the normal homeostasis between osteoclastic and osteoblastic activity. The disease is becoming less prevalent, having a later onset and showing decline in extent and severity. It may mimic other pathology such as malignancy, and in fact, pagetic bone is at increased risk of malignant transformation itself. This poses a challenge in clinical practice given that this disease affects elderly where the risk of primary and secondary neoplasia is already high. In this chapter, we describe the disease epidemiology, aetiology, and imaging features. We discuss its neoplastic and tumour-like complications in more detail.