Take a look at this New York Times article about the unprecedented lengths both campaigns have gone to conceal the health histories of their candidates. It’s worth reading in full, but here are the Cliff Notes:
McCain: Granted a limited number reporters brief access to over a 1,000 pages of medical documents. Questions remain on the severity of his melanoma, which has reoccurred a number of times.
Obama: Released only a one-page letter from his doctor testifying to “excellent” health. Appears to nurse an on-again, off-again smoking habit, the full extent of which is unknown.
Biden: Campaign-approved doctors have been interviewed about Biden and records pertaining to his 1988 brain aneurysm have been released. According to the Times, “it is not known whether Mr. Biden has had recent brain imaging scans or has been evaluated by a neurologist or neurosurgeon recently.”
Palin: No medical records of any kind have been released, keeping persistent rumors about the birth of her youngest son from being dispelled.