Neonatal ABO hemolysis is a relatively serious disease that occurs between a mother with blood type O and a child with blood type A or B. Because ABO blood types are more common in the environment, the disease can develop in the first child. The manifestation of ABO hemolysis in newborns is the rapid onset of jaundice within the first 24 hours of life, with a rapid increase in jaundice values and a predominance of unconjugated bilirubin in the serum, accompanied by varying degrees of anemia. Because of the rapid rise in serum bilirubin, the disease is easily combined with bilirubin encephalopathy, which is the most serious complication of neonatal hemolytic disease and occurs mostly within the first week of life. If the mother has O blood type and the child has a possible A or B blood type, parents must closely monitor the change in the jaundice value of the child. If jaundice appears within 24 hours, it should be reported to the doctor and actively treated with phototherapy to avoid serious complications.