Leiomyosarcomas (LMS) are soft tissue tumours derived from smooth muscles cells, often in the uterus, retroperitoneum, skin, vessels, and bone. They are one of the most common types of sarcoma. Most leiomyosarcomas are sporadic, but may develop in the setting of genetic syndomes such as hereditary retinoblastoma and L-Fraumeni syndrome. Leiomyosarcomas may also be a result of radiation exposure; however, radiation-induced sarcomas are typically undifferentiated, fibrosarcomas or malignant peripheral nerve sheath tumors. Like other sarcomas, prognosis is worse with higher grade tumours. Although chemotherapy and radiation are sometimes used as adjuvant therapy, the mainstay of therapy, and the only chance for cure, is surgery. The management of LMS is especially complex when the tumour involves major blood vessels. This book discusses the diagnosis and treatments most effectively used for Leiomyosarcomas. It also provides insight on the specific areas that LMS is found and how it affects that area.