This document provides an overview of antineoplastic agents (chemotherapies) used to treat cancer. It begins by defining a neoplasm or tumor and describing the causes and types of cancer. It then discusses factors that affect cancer incidence and classifies antineoplastic drugs. The main classes described are alkylating agents, antimetabolites, antibiotics, plant products, and miscellaneous drugs. For each drug class and some individual drugs, the document provides details on mechanisms of action and specific uses to treat different cancer types. It concludes by covering the synthesis of some example antineoplastic agents including mechlorethamine, methotrexate, and mercaptopurine.