INTRODUCTION: Dose-limiting hematological toxicity is encountered with many chemotherapy regimens; it is common clinical practice to reduce the dosage or delay the administration of the next cycle of chemotherapy in response to toxicity [1, 2]. Reducing or delaying the dose, however, will reduce the dose intensity of treatment. This practice may achieve some reduction in toxicity, but may also decrease the therapeutic effect of the treatment. This review will examine the evidence for a relationship between reductions in dose intensity of treatment and suboptimal outcome, as distinct from studies seeking to improve survival by using dose-intensified chemotherapy regimens.