Tymoshenko, the fiercest opponent of President Viktor Yanukovich, was condemned for overstepping her powers in forcing through a gas deal with Russia in 2009. The European Union and United States said the trial was politically motivated.
The former prime minister dismissed the original trial as part of a campaign by Yanukovich to rid himself of a political rival, and filed an appeal. But on Thursday she and her lawyers accused the appeals court of being biased and said there was no hope for a fair trial.
"I have decided to refuse to take part in this shameful process and not to appeal the decisions of the two courts," she said in a statement. "Seeking truth and justice in Ukrainian courts is an absolutely useless task."