Jul 12, 2007
Archaeologists believe the pieces of copper alloy date from the middle of the 4th Century.
They were found in a sand dune, but the location in the Uists has been kept secret to protect the site.
Archaeologists said it was a "lucky find" as the coins were at risk of vanishing in a high tide.
Just seven other Roman coins have previously been found on the isles.
A Roman brooch and pieces of pottery have also been uncovered in the past.
Kate Macdonald, an archaeologist who has lived on the isles for three-and-a-half years, said the new find was exciting.
She said: "It is very unusual to find two coins very close together on a stretch of beach on the Western Isles.
"A whole seven others have been found - six of those on North Uist - which indicates something quite special was happening at that time."
Ms Macdonald is studying a PhD at the University of Sheffield on the Iron Age, Scottish islands and brochs.
She said the coins dated from the Iron Age in Scottish terms, but in England would be considered to be from the late Roman period.
The isles were a "hub of development" throughout pre-history because travel was easier by sea than land at that time, said Ms Macdonald.
However, she said it was likely to always remain a mystery how the coins arrived on the islands.
They were either brought back by islanders from the mainland, or by Romans.
Ms Macdonald said: "In Scotland it has always been thought the Western Isles were beyond the reach of the Roman Empire."
She added: "The coins were very well preserved.
"You would expect salty water might have attacked them to some extent. They look almost as good as the day they were made."
The coins are being kept at a local museum, but will eventually be examined by experts in Edinburgh.
Ms Macdonald praised the members of public who found them for handing them over the museum.
Archaeologists are convinced that no other coins are on the beach after an extensive scan of the area using metal detectors.
Meanwhile, Fife charity Scottish Coastal Archaeology and the Problem of Erosion (Scape) is leading a community project at a site on North Uist.
Scape is investigating the suspected Iron Age round houses before they vanish in a powerful storm.
The University of St Andrews-based organisation is also carrying out work at another historic site in Brora.