What is Tsunade's chakra element? In the series, she is celebrated as the world's best medical-nin, and is one of Konohagakure's Legendary Three Ninja. What is her chakra element?
I don't think it was officially announced. It's just like Sakura's case.

From Naruto Wikia, we find that:


  Tsunade's Nature Types consists of Fire,  Lightning, Earth, Water, Yin (anime only) and Yang Release.