Everyone is talking about it ... the elevator brawl between Jay Z & his sister-in-law, Solange Knowles.

Actually, it wasn't a brawl, because Jay Z didn't attack back, he was just in self-defense mode the whole time.

But it happened a little over a week ago, after the big Met Gala party they have in New York City every year. The three went to an after party and then got into an elevator to leave.

For some reason, Solange started attacking Jay Z. There's no audio in the video, so we don't know what was said, but the video goes on for over three minutes & even when the bodyguard was holding Solange back, you could tell she was yelling at Jay Z.

It's quite a video.