From what I understand they can juice all they want in training, but as long as it's out of their systems come fight time they're ok. But that's still a big change from the PRIDE days when you can have to full benefits of steroids during the fight. I've heard UFC fighters might start getting randomly tested though.
Also, growth hormone is pretty much untestable, so if a fighter can afford it there's really nothing to stop them from using.
Also, growth hormone is pretty much untestable, so if a fighter can afford it there's really nothing to stop them from using.