Michael Jackson is suffering from a lung disease and needs a transplant. The disease is rare and can be fatal. According to the biographer of his book:

‘He’s had it for years, but it’s gotten worse,’ Halperin said in an interview In Touch magazine. `”He needs a lung transplant but may be too weak to go through with it. He also has emphysema and chronic gastrointestinal bleeding, which his doctors have had a lot of trouble stopping. It’s the bleeding that is the most problematic part. It could kill him.’

I feel so sorry for MJ he's lived a really messed up life.