Originally Posted by Miu
I think I'm missing something here... I don't remember reading a part wherein Kakashi kew that Tobi was Madara...
Thanks for joining me in here by the way ^^
Well it was never stated that Kakashi knows Tobi is Madara, but Kakashi did see his sharingan and the level of Madaras space/time ninjutsu surpasses the 4ths. So we are assuming that Kakashi at least has an idea about who he is.