The mammillary bodies are a pair of small round bodies in the brain forming part of the limbic system. They are located at the ends of the anterior arches of the fornix, and are named mammillary for their resemblance to two breasts. They consist of two groups of nuclei, the medial and lateral nuclei. They are connected to other parts of the brain as shown in the schematics below.



The mammillary bodies are parts of the brain known to be significantly damaged by alcohol intoxication, especially by chronic alcohol abuse and associated deficiency of thiamine. Researchers in 1998 also noted visible abnormalities in the mammillary bodies of individuals with autism.

Damage to the mammillary bodies due to thiamine deficiency is implied in pathogenesis of Wernicke-Korsakoff syndrome. Symptoms include impaired memory, also called anterograde amnesia; this suggests that the mammillary bodies might be important for memory.