A prince du sang or prince of the blood is a person legitimately descended in male line from a sovereign. The female equivalent is princess of the blood, being applied to the daughter of a prince of the blood. The most prominent examples include members of the French royal line, but the term prince of the blood has been used in other families more generally, for example among the British royal family and when referring to the Shinnōke in Japan.

Fils de France was the style and rank held by the sons of the kings and dauphins of France. A daughter was known as a fille de France.