 At the end of 1563, together with two relatives of Grand Chancellor and Pidrikis Skuminas (Tiškevičius), Giedraitis enrolled into the University of Leipzig.As it was quite common at the time, Giedraitis did not earn an academic degree.Giedraitis studied at four Protestant universities and was close with some Protestant activists, but there is no evidence that he converted to Protestantism – documents related to his appointment as bishop are silent on the issue.