Is a chicken undercooked if there is blood inside?

No, the presence of blood inside a cooked chicken does not necessarily mean it is undercooked. The color of meat and juices is not always a reliable indicator of doneness. The safest way to ensure a chicken is fully cooked is to use a meat thermometer to measure its internal temperature. According to the USDA, chicken should be cooked to an internal temperature of 165 degrees Fahrenheit to ensure that any harmful bacteria are killed.