Endoscopic ultrasound (EUS) is central to the diagnosis and staging of many malignancies, but now has an evolving role in cancer therapy. EUS-guided fine needle injection (FNI) is already used for palliative interventions such as treatment of pain through nerve blockade and to guide biliary decompression when conventional ERCP is not possible. More recently, EUS-FNI has been used to deliver specific anti-tumor agents for pancreatic cyst ablation and local control of tumor growth in patients with unresectable solid malignancies. The agents used to date include ethanol, brachytherapy seeds, and chemotherapeutic agents such as paclitaxel. In addition, FNI of new immunomodulating cell cultures such as mixed lymphocyte and dendritic cell cultures has also been reported, as has FNI of several different viral vectors for antitumor therapy. Although experience with these agents remains preliminary, EUS-FNI is a minimally invasive approach to deliver local antitumor agents, and is likely to have an expanding role in cancer therapy.