A 3-month-old girl presented with a 6-week history of a curvilinear hyperpigmented patch on the left wrist, which began within a day of using a tight mitten. Mitten-line hyperpigmentation is analogous to the recently described condition known as infantile "sock-line hyperpigmentation," or more generally "sock-line bands." Distinguishing this benign condition from child abuse, amniotic band syndrome, and acquired raised bands of infancy is important but sometimes challenging.