The anterior fontanelle (bregmatic fontanelle, frontal fontanelle) is the largest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture; it is lozenge-shaped, and measures about 4 cm in its antero-posterior and 2.5 cm in its transverse diameter.

The anterior fontanelle typically closes between the ages of 12 and 18 months.

Examination of an infant includes palpating the anterior fontanelle.

A sunken fontanelle indicates dehydration whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure.

However, this is not a certain indicator for raised pressure as prolonged crying by the baby may produce the same effect.