The Council of Rimini (also called the Council of Ariminum) was a Christian church council that took place in Rimini (Latin name, Ariminum) in July 359, and was concerned with the problem of Arianism. Over 400 bishops of the Western Roman Empire attended, failing to resolve the Arian controversy over the divinity of Jesus Christ, an aspect of the problems of Christology that divided the fourth century Church. The council was called by the pro-Arian Roman Emperor Constantius II.

Two synods actually took place at Rimini and at Seleucia simultaneously. The synod for the Eastern bishops held at Seleucia Isauria (now Silifke, Turkey), was called the Council of Seleucia.

Orthodox bishops who are known to have attended at Rimini include:

• Phaebadius (Fiari, Phebade) of
  
  
  
  Agen (died c. 392)
• Servatus (Servais) of Tongeren (died May 13, 384)
• Gaudentius (Gaudenzo; Gaudenzio) of Rimini (died October 14, 360)
• Mercurialis of Forli
• Restitutus of Carthage

At the Council of Rimini, the orthodox bishops were outmaneuvered by the Semi-Arian bishops. The Semi-Arian bishops, whose numbers included Ursacius, Valens, Germinius, and Auxentius, adopted a formula concerning the relation of the Son to the Father (to the effect that the Son is not a creature like other creatures), to which the orthodox bishops agreed.

Pope Liberius, who had not been present at the council, rejected the formula, at which point many of the orthodox bishops repudiated their signatures, including Phaebadius and Servatus .

The Council was considered a defeat for orthodoxy, and Jerome wrote, "The whole world groaned in astonishment to find itself Arian".