"The twins, both of them males, were born Thursday of a mother gorilla called Kabatwa. They are doing well," Radio Rwanda reported, quoting information from the Rwandan Development Bureau.
According to the pro-government daily New Times, only five previous instances of twins have been recorded in 40 years of monitoring in Rwanda.
"It`s uncommon among the population of gorillas, and very few cases of twins have been documented in the wild or captivity," said Prosper Uwingeli, chief warden at the Volcanoes National Park where the twins were born.
According to a 2010 census, the total number of mountain gorillas has increased by a quarter over the past seven years to reach more than 780 individuals.
Two thirds of them are found in the Virunga massif, which straddles Rwanda, Uganda and the Democratic Republic of Congo.
Mountain gorillas are Rwanda`s main tourist attraction.