Neoadjuvant chemotherapy or chemoradiotherapy is an important concept in the treatment of colorectal liver metastasis, gastric cancer, and esophageal or rectal tumors. This treatment strategy improves disease-free survival and sometimes overall survival. It allows surgical resection of lesions that where not resectable at diagnosis. The new standards of neoadjuvant treatments in gastrointestinal oncology are described in this article.