Ten rhino horns, with an estimated value of €500,000, have been seized by Customs officials at Shannon Airport.
Three people are likely to face court proceedings in connection with the haul.
The items were seized during three separate searches in recent weeks by customs officers at Shannon airport.
They were found in the suitcases of three people, all Irish, who were attempting to smuggle them through the airport.
Six are from white rhinos, which are an endangered species, and four are from black rhinos, a breed which is also now critically endangered.
The seizures were made under an international convention known as CITES, which aims to stop international trade in endangered species.
The horns are sometimes ground down to be used in traditional Chinese medicine.
This haul is of international significance as seizures like this are very rare. The only comparable one was in South Africa last year.
The customs investigations unit is now working on bringing a prosecution against a number of people in the courts.