At the ceremony Tuesday in Washington, the president said the world will never know the names of all those who perished at the hands of communists.
But he said there is an obligation to pay tribute to their lives and honor the memory of the more than 100 million innocent men, women and children who died under communism worldwide. He said the exact number of victims will never be known.
Mr. Bush noted the suffering of those who perished under communist forces in China, Afghanistan, North Korea, Africa, eastern Europe and the Soviet Union, Cambodia, Cuba and Vietnam.
The memorial, located near the U.S. Capitol building, features a bronze replica of the Goddess of Democracy erected in Tiananmen Square protests in China in 1989. It is based on the U.S. Statue of Liberty.
U.S. Congressman and Holocaust survivor Tom Lantos said it is his privilege to continue working to bring about a recognition that the wave of the future is not, as he put it, Godless communism or Islamic radicalism but free and open democratic societies.
The Victims of Communism Memorial Foundation says communism continues to enslave one fifth of the world's population today. The foundation was created by Congress to build the memorial.
After the ceremony, the Heritage Foundation hosts a forum with prominent, long-time political prisoners from communist regimes, including Harry Wu of China, poet Nguyen Chi Thien and Tu Tranh Tran of Vietnam, and Pedro Fuentes of Cuba.