Speaking at a brief press conference before checking out of the elite Rudolfinerhaus clinic, Yushchenko lauded the decision of thousands in Ukraine to take to the streets to protest the outcome of presidential elections there.
"We haven't seen anything like that for the past 100 years," he said. "I think it would be appropriate to compare this to the fall of the Soviet Union or the fall of the Berlin Wall."
Yushchenko thanked the medical staff, who determined he had been poisoned, which caused his dramatic facial disfigurement.
"They've spent many days and nights with me and I am very happy to be alive in this world today," he said. "I thank these people for this."
Doctors say he will be able to return to the campaign trail, but that it could be two to three years before his face heals.
Supporters of Yushchenko expressed little surprise over revelations from a hospital in Austria that he was poisoned.
But campaigners for his opponent, Viktor Yanukovych, rushed to reject suggestions that the prime minister could have been involved in the poisoning.
There is "no logic in such an accusation," said Taras Chornovyl, Yanukovych's campaign manager on Saturday.
Suspicion will may even fall on the Kremlin, reports CBS News Correspondent Tom Fenton, who notes Moscow fears Yushchenko will take Ukraine out of Russia's orbit by joining NATO and the European Union.
"But," adds Fenton, "it looks like this will now propel him into office, unless something else happens to him before the election."
A Russian health ministry official questioned the doctors' conclusions, saying in a radio interview that dioxin does not work immediately.
Yushchenko's backers who were still camped out at Independence Square — the epicenter of protest over the disputed presidential election runoff — milled around and passed the news by word of mouth. Many shook their heads sadly.
"Everybody knew he was poisoned so we didn't really need official tests," said Anatoly Klotchyk, 19, who stood in the sleet outside his tent near the square.
Another activist in the tent camp, Yuriy Krynychenko, 22, said Yushchenko's symptoms — including a swollen, discolored face — left no doubt. "His face spoke for itself," Krynychenko said. "We knew he was poisoned. The intelligent people will now understand ... what criminals our authorities are."
Lawmakers such as Ihor Ostash, from Yushchenko's Our Ukraine party, said the results from the hospital in Austria confirmed what Yushchenko's backers already believed — that Yushchenko's opponents wanted to assassinate him rather than take the risk he would beat Yanukovych in the presidential election.
"Politicians don't have simple human sympathy," he said.
However, Yanukovych's former representative on the Central Election Commission, Stepan Havrysh, questioned the statement from Austria, saying that while he felt sorry for Yushchenko, "I'm afraid, two weeks before the vote, it's all political."
Havrysh called the issue "a painful theme for Ukrainian democracy."
Doctors in Vienna said Saturday that dioxin poisoning caused Yushchenko's mysterious illness, adding it could have been put in his soup.
Yushchenko is now in satisfactory condition and his dioxin levels have returned to normal, Dr. Michael Zimpfer, director of Vienna's private Rudolfinerhaus clinic, told a news conference. Dr. Nikolai Korpan also said, "No functional damage will remain."
Doctors said he should be able to work normally and his dramatic facial disfigurement should heal.
"There is no doubt about the fact that Mr. Yushchenko's disease has been caused by a case of poisoning by dioxin," Zimpfer said. Tests run over the past 24 hours provided conclusive evidence of the poisoning, Zimpfer continued.
"We suspect involvement of an external party, but we cannot answer as to who cooked what or who was with him while he ate," Zimpfer said, adding that tests showed the dioxin was taken orally.
Zimpfer said Yushchenko's blood and tissue registered concentrations of dioxin 1,000 times above normal levels.
"It would be quite easy to administer this amount in a soup," Zimpfer said.
The substance containing the dioxin would most likely have been consumed the day he fell ill, as dioxin is rapidly absorbed, Zimpfer said.
"This substance led to quite a significant increase in the (dioxin) level within just a few hours and this intake then led to the quite devastating effects that we have seen," he said.
"The substance started to wreak havoc in the body."
A parliamentary commission that investigated Yushchenko's mysterious illness in October said he complained of pains after meeting with the head of Ukraine's Secret Service Ihor Smeshko, but lists other places he ate or drank that day. Smeshko promised the secret service would investigate.
Unlike earlier blood tests, the latest were sent to a laboratory in Amsterdam that uses a new analysis method that could test it for dioxin, Korpan said.
When first seen by the Austrian doctors, Yushchenko was in a "critical stage" but was "not on the verge of dying," Zimpfer said.
"If this dose had been higher, it may have caused death," Zimpfer said.
Dioxin is formed as a by-product from industrial processes such as waste incineration, chemical and pesticide manufacturing and pulp and paper bleaching.
They are a normal contaminant in many foods, but a single high dose, usually in food, can trigger illness, London-based toxicologist John Henry said last month.
Shortly after the announcement of the diagnosis on Saturday, Henry told British Broadcasting Corp. television that Yushchenko's case was, in his experience, unique.
"We've never had a case like this, a known case of large, severe dioxin poisoning ... It's normally fairly mild. It can cause liver damage."
"It's usually low-level, long-term poisoning. A very large dose, nobody has any real idea of what it would cause. Now we do know."
Yushchenko first fell ill in September and was rushed to the elite Vienna hospital after complaining of excruciating back pain. He resumed campaigning later in the month but with a pockmarked and badly disfigured face.
He returned to the hospital later in September for further treatment and checked in for a third time Friday.