The Grammy Award-winning artist has battled drug and alcohol addiction for years.
Her show in Belgrade Saturday night was to mark the start of a series of comeback concerts; however, she stumbled and slurred so badly during the performance she was booed off the stage.
Winehouse's publicist Tracey Miller told CNN Sunday: "Yes, Amy has canceled appearances in Istanbul and Athens for the coming week. Despite feeling sure that she wanted to fulfill these commitments, she has agreed with management that she cannot perform to the best of her ability and will return home."
Miller did not say if Winehouse had started using drugs again, CNN reported.