Cytotoxic drugs are a unique therapeutic class of fundamental importance in current antineoplastic chemotherapy. These drugs belong to many chemical and chemotherapeutic classes. They are cytotoxic by design and are able to cause serious dose-limiting adverse effects at therapeutic doses. Most antineoplastic dosing strategies focus on minimizing cytotoxicity rather than optimizing efficacy. In turn, cytotoxicity is interconnected with other therapeutic considerations, including cell status (renewing vs. non-renewing cell types), cell membrane transport integrity, intracellular activation status, immune system integrity, cellular repair status, and drug resistance. Regulatory requirements for the development of cytotoxic drugs are not well characterized, and differences exist in regional requirements. A safety assessment package which is utilized and accepted world-wide does not yet exist, despite many efforts of harmonization. In this report, the authors introduce a comprehensive safety assessment package for cytotoxic drugs, based on institutional experience acquired globally with this class of drugs, that fulfills both scientific and world-wide regulatory requirements for this very important therapeutic category.