The mainstay of treatment for adults with soft-tissue sarcomas is wide surgical excision. Half of all patients with adequate local control of high-grade sarcomas develop distant metastases and, despite additional treatment, ultimately die from their disease. This daunting reality has resulted in a three-decade research effort to assess the efficacy of adjuvant therapy for adult soft-tissue sarcomas. The multitude of histopathological subtypes, each with its own biology and clinical behavior, and the rarity of adult soft-tissue sarcomas as a whole greatly complicate such an assessment. This Perspectives article examines data that support or refute the use of adjuvant chemotherapy in the treatment of soft-tissue sarcomas.