Stoa Amphiaraion (also known as the Enkoimeterion) is located on the east side of the Sanctuary of Amphiaraios, southeast of the Theater. It was built circa 360 BCE. The two-aisled stoa opens towards the southeast with an outer Doric colonnade of forty-one columns and an inner Ionic colonnade of 17 columns. Before its destruction, two small rooms was separated from the rest of the stoa by two columns with a screen between them , with a bench running the length of the back wall.

Pilgrims would migrate to the stoa and sleep there, awaiting an oracle's advice. It is a possibilty that the rooms may have been for female pilgrims. A level area in front of the stoa may have been used as a track.

It is a probable that this stoa replaced an existing one, located farther southwest on the terrace where the later row of dedications stood.