On a personal level, the frail 96-year-old's congressional appearance is to be a sweet vindiction for a family whose influence has steadily withered since her husband, General Chiang Kai-shek, died in 1975. But the visit was also likely to remind China of the United States' historical support for Peking's enemy - Taiwan's Nationalists - at a time when the three countries' triangular relationship could hardly be more convoluted.
"This invitation from the United States Congress to my mother is an honour of the highest degree," Chiang Wego, the son of General Chiang, said.
"This gives her great respect and through her it gives us Chinese people great respect," added Mr Chiang, 79.
Madame Chiang, who lives in Long Island, New York state,does not hold any government post in Taiwan. But despite her lack of influence in Taipei, a ceremony to fete her in the halls of US power will be taken as a supreme snub by Peking. "Perhaps there is no other figure alive who can elicit such hated memories for China's old rulers as Madame Chiang," said a foreign diplomat in Taipei.
The ceremony coincides with a rising tide of pro-Taiwan feeling in Congress. Earlier this month, the House Speaker, Newt Gingrich, suggested that Washington should recognise Taiwan, with which it broke off diplomatic relations in 1979. He later withdrew the idea.
In the US too, memories may stir of the woman who drew thunderous applause from Congress in 1943 as she drummed up American support for the Nationalists' unsuccessful battles against China's Communists.