Thai authorities have seized 21 rhinoceros horns smuggled from Ethiopia worth almost five million dollars (£4.1 million).
The bags carrying the horns were discovered in a random customs search at Bangkok's main airport.
The bags' owners fled as officers searched their bags and have not been apprehended.
Customs officials said the horns are unusually large and pristine.
It is the second time in two years that rhino horns have been seized at the airport.
Rhinoceros horns, blood, skin and urine are in high demand across Asia for their use in traditional Chinese medicine.
The World Wildlife Fund says very few rhinos survive outside national parks and reserves, and some species are endangered.
Experts who examined the smuggled horns concluded that the poachers who obtained them must have killed the rhinos.