The current practice of dosing patients with anticancer drugs based on body size, leads to a large degree of interpatient variation in clinical outcome following standard doses of chemotherapy. Some patients may fail to respond to treatment, whilst others experience unacceptable side effects. Recent studies have identified more rational approaches to drug dosing, based on patient characteristics such as renal function, pharmacogenetic factors, and drug metabolizing activity. These can be used together with therapeutic drug monitoring and adaptive dosing to achieve a targeted systemic drug exposure in each patient, which may lead to more consistent clinical outcomes in patients receiving comparable chemotherapy dosing regimens. The purpose of this review is to present some approaches to chemotherapy individualization, examples of how this might be applied, and speculation as to how recent advances in pharmacogenetics may lead to further dose-optimization. Whilst it is hoped that the design of new agents, targeted to specific genes involved in oncogenesis, will lead to increased success in the treatment of cancer patients, it is essential that the drugs currently available are used to their maximum potential.