The frontal bone is one of four main bones which make up the vault of the cranium of the skull, the others being the two parietal bones and the occipital bone. At birth it consists of right and left halves, joined by a suture that usually closes during infancy.

The frontal bone has two parts: the vertical portion, called the squama frontalis, which comprises the substance of the forehead; and the orbital or horizontal portion, called the pars orbitalis, which overhangs the orbital cavities (see orbit) in front. Separating the frontal bone and the parietals is the coronal suture.

The frontal bone contains several air sinuses, known as parasinuses.