This study presents several forgeries which – unless identified – disrupt early 4th c. Roman numismatics. Late Roman coin forgeries are nothing new and many public collections include forgeries, often unknowingly. In addition, forgeries in increasing numbers have been entering the commercial market. Undetected old and new forgeries pose the same problem: they disturb research by introducing false data. The outcome of studies may be skewed or outright wrong. New evidence shows that the famous PLVRA NATAL FEL coin, purportedly struck for Constantine I’s 50th birthday, is a forgery. This “evidence” for the emperor’s age must be disregarded. Other studies affected by forgeries include: Christian symbols on coins (SPES PVBLIC forgeries; “emperor holding labarum” forgeries); 1/24 pound silver AVGVSTVS / CAESAR medallions: false “trial strikes” of gold donatives, in themselves forgeries; in fact a flood of “Late Roman” forgeries in all metals threaten to disturb or obstruct whole areas of numismatic research.