But it's not as simple as just knowing one number anymore.
Doctors like Christopher Cannon are taking a second look at the relationship between good cholesterol, known as HDL, and bad cholesterol known as LDL.
"The two really need to be unlinked," says Dr. Christopher Cannon. "We used to think of them together, now we have to think of them separately."
Bad cholesterol has traditionally been the villain, the artery-clogging stuff statin drugs were developed to get rid of. Good cholesterol actually helps clear the arteries. Unlinking the two is creating some treatment dilemmas reports CBS News Correspondent Elizabeth Kaledin.
Mary Newman's good cholesterol is fine but her bad cholesterol is a problem. She's been trying to control her it with diet and exercise.
"I am very leery of taking medications and I wanted to stay off medication," says Newman,
But doctors have learned that good cholesterol doesn't counteract the bad, and diet and exercise alone don't work. They've recommended that Newman start taking statins.
"Our guidelines from 10 years ago would not have said she needed treatment," says Cannon. "The benefits of lowering the bad cholesterol are really independent of what your good cholesterol is."
Dan Keller has the opposite problem: his bad cholesterol level is fine, his good cholesterol is too low.
His doctor Daniel Rader says we now know that not enough good cholesterol can be equally deadly.
"Low HDL is one of the most common risk factors for heart disease," says Rader.
Keller is participating in a small trial of a brand new drug called Torcetrapib that has doubled his good cholesterol in just 8 weeks.
Keller says the results were amazing.
Pfizer is developing the drug, the first of its kind to try to improve levels of good cholesterol. Rader believes if it works, combined with statins, treatment will take a giant step forward.
"Everybody should know that the good cholesterol - HDL - is the new frontier where new therapies that are going to be developed are going to revolutionize our ability to prevent heart disease," says Rader.
In the meantime, the recommendation is keep checking your cholesterol. And in addition, always know the good and the bad, so you can avoid the ugly: heart disease.