The work deals with the two Ecclesiastical histories.one is written by Rufinus of Aquileia, and the second one by bishop of Cyprus, Theodoretus. One is considered the father of the western (Latin) church history writing, while Theodoretus is а saint in the Orthodox church and a great theologian, in spite of his connections with Origenus and his theology. Their histories are not the most improtant sources for the church history of Sirmium, but they provide some very interesting data. The most important information given by Rufinus of Aquileia and Theodoret are one on Photinus, the bishop of Sirmium and haeretic. Rufinus in his work mentions the Council of Nicea alongside its canons. According to one followers of Paul of Samosathe should be rebaptized. Another name which he uses for them is Photinians. So, in Rufinus’ work the root of the Photinian teaching is in the haeresy of Paul. While on the other side Theodoretus gives a letter of pope Damasus to one bishop where he anathematized Photin, as an Ebonian, i.e. the continuator of the Ebonites’ learning. This old haeresy is connected with Torah and the key opinion on Jesus that he was an ordinary, plain man. Here we see the connection with Photinus. Other data provided by Rufinus of Aquileia are of secondary importance, but they also can be of some assistance while more thoroughly investigating and researching Arian controversises in Europe, and as well in Sirmium, the Arian center of the time.