Adult soft-tissue sarcoma is rare but aggressive, with incidence around 5 per 100,000 per year. Head and neck locations are infrequent. Genetic disease and irradiation are risk factors. The diagnosis needs to be known in order to avoid treatment delay. There are about 50 histologic subtypes, with different patterns and prognoses. Pathologic review and the development of molecular techniques are therefore essential. Prognosis in adult head and neck soft-tissue sarcoma (HNSTS) is poor: 5-year overall survival, about 60%. Recurrence is most often local. Prognostic factors are: tumor size and local extension, histologic grade and margin status. There are few targeted management guidelines. Surgical resection with negative margins is the primary treatment. Postoperative radiation therapy can improve prognosis. The role of chemotherapy is not well established. HNSTS should be treated in a reference center, with multidisciplinary staff following national network guidelines. Several factors are still unknown. The purpose of this article is to summarize the state of knowledge in adult HNSTS.