Wise and just seer who was married to Eriphyle, the sister of king Adratos of Argos.
Adratos wanted Amphiaraos to join him in the attack of the Seven against Thebes, but the seer refused at first, since he knew the war would end unhappily.
The son of Oedipus, Polynikes, was the one to have instigated the plan and he managed to bribe Eriphyle into convincing her husband to go. He gave her the necklace of Harmonia, which she in turned had received from her husband Cadmus, founder of Thebes. The necklace had been made by the god Hephaestus.
When in Thebes, Amphiaraos found himself being chased by the Thebans, but was rescued by Zeus. The god split open the earth, and so the seer and his chariot disappeared down in the underground.
The sacred site Amphiareion was dedicated to the seer, and was built at Mt. Oropos, between Boeotia and Attica. The sick ade pilgrimages there in antiquity to get visions of a cure. Today this site has been found and excavated.