The assessment of lymphadenopathy in children is a common diagnostic problem in pediatrics. An understanding of the wide variety of diseases and conditions that may present as lymphadenopathy is essential to determining the most appropriate work up for an individual patient. Although the majority of these children will prove to have a benign disorder, it is important that the pediatrician also have an appreciation for the malignant diseases that may present with lymphadenopathy, so that in such cases the diagnosis of a serious or life-threatening disease can be made in a timely manner.