The pineal gland, or epiphysis, is a small endocrine gland located near the middle of the brain.

The pineal body is located above the superior colliculus and behind and beneath the stria medullaris, between the laterally positioned thalamic bodies. The pineal body is part of the epithalamus.

It is responsible for the production of melatonin, which has a role in circadian rhythm. Melatonin is a derivative of the amino acid tryptophan. The production of melatonin by the pineal gland is stimulated by darkness and inhibited by light.

The pineal gland is a midline structure and is often seen in plain skull X-rays as it is often calcified.