Simminensis is an ancient and titular episcopal see of the Roman province of Africa Proconsularis in modern Tunisia, and a suffragan diocese of the Archdiocese of Carthage.
Founded in the Roman era only one bishop is known for certain from antiquity, St. Fiorenzo, who participated in the Council of Carthage (484) convened by the Vandal king Huneric, after which he was exiled to Corsica .
The first Deuterium Simminensis is mentioned in the Notitia Africae of 484AD, while the second Iunianus or Martin[7] took part in the Council of Carthage (525).
It would appear to have been somewhere on the north-western coast of Cap Bon 30 km east of Carthage.
[13] While Tissot in turn suspected the ancient city to the south, at Henchir Bir Djedi.