Paget's disease of bone (PDB) is a condition of unknown etiology characterized by excessive and abnormal bone remodeling. It may be localized to one or several skeletal segments. The disease seldom appears before the age of 40 years, but its prevalence tends to double each decade from the age of 50 onwards, reaching about 10% after ninth decade. PDB may virtually affect every bone in the skeleton. Affected bones are involved right away with no new involvement during the evolution. The basic symptom of the disease is bone pain, while complications depend on skeletal sites involved and range from secondary osteoarthritis to malignant degeneration. Diagnosis is usually based upon clinical features, imaging, and laboratory analyses. Therapeutic approach is currently based on second-generation bisphosphonates. Their use is recommended when bone alkaline phosphatase is high and/or when the disease localizations are highly suspected for determining complications.