The term Mongolian Spot or Mongolian Blue Spot refers to a bluish-gray birthmark usually on the sacral area of normal infants. It is a macular condition, and may look somewhat like a rash. It normally vanishes three to five years after birth.

Mongolian spot is a congenital developmental condition exclusively involving the skin. It results from the entrapment of melanocytes in the dermis during their movement from the neural crest into the epidermis. The condition is not linked to sex, and both male and female infants are equally predisposed to Mongolian Spot. It does not carry with it any health risks.

Mongolian Spot is most common among Mongols and other Asian ethnic groups (Korean, Japanese, Indonesians , Amerindians, etc.), occurring to some degree in approximately +95% of Mongolian infants, 80% of East Asian infants, 40-50% of Hispanic infants, and 1-10% of Caucasian infants.

It might sometimes be mistaken for abuse bruises by over-zealous social workers or medical staff who are not aware of the condition.