Pathological fractures are defined as fractures that occur in patients with weakened bone due to systemic and local diseases. If osteoporosis is excluded, the frequency amounts to 5% of all fractures treated. The main diagnostic aim is to observe the pathological nature of the fracture and to perform interdisciplinary, causal therapy. For this, diagnostic and therapeutic algorithms are demonstrated, arranged according to osteopathies, constitution anomalies, myelogenous and inflammatory bone diseases, primary and secondary bone tumors and posttraumatic/postoperative disorders. These algorithms should help the trauma and orthopedic surgeon to select the proper conservative and operative therapy and to use all resection and reconstruction possibilities, such as osteosynthesis, alloarthroplasty and bone transplantation.