Lee died from swelling of the brain, brought on by a reaction to painkillers given to him be an actress he was visiting. His death is a general mystery though. I read up on him in wiki....he was in extremely, outstanding, physical condition when he died, but the autopsy left them puzzled as to the cause of death. the swelling in his head was 13% greater than normal...sad.

The answer given above is correct. Bruce died from an allergic reaction to an ingredient found in the pill Equigesic, which was given to him by actress Betty Ting Pei when he had a headache and went to lay down. However, mere months before, he nearly died as well from brain swelling. The most likely cause of this is that he suffered many blows to the head throughout his career like any other fighter and he most likely had a brain aneurysm. There are many other theories. The bit of cannabis found in Bruce's system when he died doesn't seem to have been a contributing factor, though some have alleged a ton of allegations. Everything from Bruce being poisoned or murdered by his enemies to superstitions about a demon taking him (Chinese legend has it that when the first born of a family dies - as Bruce Lee's oldest brother did in childbirth - a demon has taken it and will come for the next born. For this reason, Bruce was named a girl's name as a baby and dressed in girls clothing the beginning years of his life to "fool" the demon. Some say it came for him and thus his son, if you believe that kind of thing). Some believe Bruce took steroids and the combination of that mixed with pot, Equigesic, and injections he got in his back for pain may have contributed. Rumors of him being killed seem to have also come out of the inexplicable fact that Betty Ting Pei didn't call paramedics until two hours after she found him unconscious. In any event, the simplest explanation is the one I believe. I also think that Bruce pushed his body to the physical limits of possibility and worked out harder than most human beings as he was addicted to physical fitness and dedicated most of his day to it and perhaps it was all too much. Like Bruce Lee's widow Linda, I prefer to think of the way Bruce lived.