Sen. John McCain is 71 years old, a survivor of an aggressive form of skin cancer. If elected, he would be the oldest man to become president.

These factors are not disqualifying, but they impose on Mr. McCain a larger duty than usual to provide detailed, timely disclosure about his health. So far, he has failed to meet this obligation to voters, even though he is now the presumed Republican nominee.

And it is not just on health issues that there is a lack of transparency in this campaign. Neither Mr. McCain nor Sen. Hillary Clinton has been forthcoming enough about financial records.

No presidential candidate should get to the point that he has locked up his party's nomination without public vetting of his health. And Mr. McCain, in particular, knows that. Early in his first run for president, in 1999, he provided an in-depth look at his medical history: 1,500 pages of medical and psychiatric records collected by a Navy project on the health of former prisoners of war. He has released precious little medical information since his surgery for melanoma in August 2000.

The McCain campaign says it will make his health documents available and arrange for follow-up questioning of the candidate's doctors on May 23. Why has it taken so long?

Last month, Mr. McCain released two years' tax returns. That is better than none. But it has long been the practice for general election presidential candidates to release tax filings going back a lot further, and Sen. Barack Obama has done just that.

The portrait of Mr. McCain's finances is particularly skimpy because his wife, Cindy McCain, has chosen not to make her separate tax returns available. Mrs. McCain, the daughter of a multimillionaire Anheuser-Busch distributor, is not the candidate, but the need to gain public trust and to air potential conflicts of interest is vital.

Last month, Hillary Clinton and her husband, former President Bill Clinton, released eight years of tax information, showing they earned $109 million over that period, much of it from book writing. The public is still owed a more complete accounting of the sources and amounts of Mrs. Clinton's speaking fees and business income. Still missing, too, is a complete list of the major donors who have been supporting the Clinton presidential library and foundation.

The extent of a candidate's candor is a good measure of how candid he or she will be in the White House.