The kidneys act as the body’s filtration system. They play a crucial role in maintaining electrolyte and fluid balance, as well as supporting growth and various bodily functions. When the kidneys are underdeveloped or injured, significant abnormalities can ensue, requiring management through diet and/or medical interventions. Diet and nutrition influence electrolyte balance, growth, fluid status, and many other aspects of kidney disease. This chapter explores how nutrition can optimize the care of patients with kidney conditions.