Desmoid tumors (also called deep fibromatoses) are rare benign tumors associated with pregnancy and Gardner syndrome. These tumors are characterized by bland-appearing fibroblasts, indistinct margins, and an ability to cause pathology by local invasion and recurrence. They arise in the abdominal cavity, in the abdominal wall, or in the extremities/trunk, each with a slightly different biologic behavior. Though they are not cancer and do not metastasize, desmoids can cause significant morbidity and occasionally death through local/regional invasion of critical structures. Treatment primarily is surgical, although radiation or systemic therapy can be beneficial to the patient when surgery is not feasible. This article highlights the biology and clinical features of desmoid tumors.