Endocrine complications are frequently observed in childhood cancer survivors (CCS); in many instances, these complications develop months to years after the completion of cancer therapy. The estimated prevalence of endocrine late effects is 50% among CCS; the main risk factors are external beam radiation that includes key endocrine organs (the hypothalamus/pituitary, thyroid and gonads) and/or alkylating agents. Novel agents targeting tumor growth have increased the options available to a small number of patients albeit with the need for treatment over long periods of time. Some of these agents, such as certain tyrosine kinase inhibitors and immune system modulators have been shown to cause permanent endocrine deficits. This chapter offers a brief summary of the conventional treatment strategies for the most common cancers of childhood and a brief overview of the endocrine late effects most commonly associated with these exposures. The impact of targeted therapies on the endocrine system will also be discussed. The aim of this chapter is to provide basic guidance to the consulting pediatric endocrinologist in preparation for the clinical encounter with a CCS. A more detailed discussion of the management of specific endocrine late effects can be found in the other chapters in this series.