Cerous iodide is a salt of lanthanide metal cerium (III) and iodide ion. In 1920s solution of cerous iodide for intravenous injection (called "introcid") was used as an antimicrobial agent for treating puerperal fever. It has shown prophylactic activity against sepsis, and was explored for its antineoplastic properties in patients with lymphogranulomatosis or inoperable solid tumors. According to the clinical reports, it has been applied with remarkable benefit, as indicated by tumor shrinkage and improved quality of life in several cases of locally advanced or metastatic tumors of different origin.