Maintaining adequate fluid and electrolyte balance is an important aspect of all patient care. The intravenous nurse's skill and expertise in starting and maintaining i.v. access is extremely vital to providing adequate fluids and electrolytes. Children and infants present unique problems in the management of fluid and electrolyte balance. Differences in rate of metabolism and body surface area are just two examples of special circumstances that affect diagnosis and management. An awareness of predisposing factors, early recognition of signs and symptoms that may be indicative of a developing problem, and knowledge of medical and nursing interventions help provide safe patient care. This article presents unique aspects of caring for infants and children, reviews important electrolytes, and discusses dehydration.