While TDM is routinely used in a number of medical fields, it has not gained wide utilization in oncology. There is a growing body of evidence demonstrating that current dosing methods based upon body surface area (BSA) are inadequate in delivering the proper drug exposure for optimal treatment effectiveness. BSA-based dosing is associated with drug plasma level variability as high as 30-fold and evidence exists that such inter- and intrapatient pharmacokinetic variability is a major contributor to toxicity and treatment failure. The use of therapeutic drug management (TDM) in oncology will not only serve to lower toxicity and improve efficacy but also help to control the escalating cost of cancer care. A recent randomized study with paclitaxel and carboplatin in NSCLC demonstrated that TDM led to lower dose intensity and significantly lower neuropathy without affecting efficacy. In another study with 5-fluorouricil (5-FU) in colorectal cancer the use TDM resulted in a majority of patients receiving higher exposure without increasing severe toxicities.