This document discusses vitamin D supplementation for breastfed infants. It begins by presenting a case of an infant with seizures from vitamin D deficiency. It then reviews the clinical presentations of acute versus chronic vitamin D deficiency. Risk factors for deficiency include limited sunlight exposure and fat malabsorption. The American Academy of Pediatrics recommends all infants receive a daily vitamin D supplement of 400IU. While breastmilk contains little vitamin D, breastfeeding is still recommended with supplementation. Oral liquid vitamin D drops are available for infants without other vitamins. However, many breastfed infants still do not receive supplements.