We describe the cases of five consecutive infants with symptomatic vitamin D deficiency and their mothers. Four of the infants were light skinned, all had poor sunlight exposure, and all were breast-fed or had diets low in vitamin D. All mothers had vitamin D deficiency. Regardless of race, infants with poor sunlight exposure and diets lacking in vitamin D are at risk for vitamin D deficiency. Mothers of these infants should be evaluated for vitamin D deficiency. Vitamin D supplementation of the breast-feeding mother at risk and her infant is recommended.