The fluoropyrimidine 5-fluorouracil (5-FU), an antimetabolite drug, works by being incorporated in the RNA and DNA and by the inhibition of the nucleotide synthetic enzyme thymidylate synthase. It is widely used in the treatment of a range of cancers, including gastrointestinal, head and neck, and breast cancers. In this book, the authors present current research in the study of the synthesis, health effects and role in chemotherapy of fluorouracil. Topics discussed include the antiproliferative activities, cell-cycle regulation, apoptosis and cellular differentiation of acyclic 5-fluorouracil O, N-Acetals; 5-fluorouracil and its immunotoxicity and side effects; 5-fluorouracil application in the management of bleb failure; and cisplatin and 5-fluorouracil for the treatment of ovarian adenocarcinoma.