Neoadjuvant therapy has come to play an increasingly prominent role in the treatment of cancer. Originally defined as systemic therapy given before local treatment, the concept has been extended to include radiation therapy given before surgery. Potential advantages include improved local and distant control, direct evaluation, and organ-sparing treatment. Potential disadvantages include increased toxicity and cost, potential delay in effective treatment, and obscuring of pathologic staging. Neoadjuvant therapy in cancer treatment may be viewed in three categories: tumors in which neoadjuvant treatment has been shown effective, thus becoming standard therapy; tumors in which it has been shown to facilitate organ-sparing, and tumors in which its utility has not been shown. For patients with osteogenic sarcoma, for example, preoperative chemotherapy and limb salvage therapy have become the standard of care. Response to chemotherapy, ascertained by histologic review of the surgical specimen, can be used to tailor postoperative chemotherapy. In patients with advanced laryngeal squamous cell carcinoma, neoadjuvant chemotherapy followed by radiation has permitted laryngeal preservation in a majority of patients without compromising overall survival. Phase II and III studies conducted in women with breast cancer have demonstrated promising results for neoadjuvant chemotherapy given before radiation therapy and/or surgery. Phase III studies to compare neoadjuvant therapy to standard therapy in patients with breast cancer are underway. For neoadjuvant therapy, as with other innovations in cancer treatment, it is crucial that a new strategy must be compared closely to standard therapy in terms of recurrence, survival, and impact on organ sparing, as well as quality of life and treatment costs.