"Now, all of the records, as far as I know, about what we did with health care, those are already available," Clinton said at the Oct. 30 Democratic debate in Philadelphia.

But a big part of that history is being concealed. Hundreds of pages of memos and correspondence involving the health-care plan of the early 1990s have been withheld.

Some of the records kept from public view are memos that White House aides wrote to Clinton about members of Congress, some of whom are still serving.

Federal archivists working at Bill Clinton's presidential library in Little Rock, Ark., deemed the material confidential. The archivists withheld it under a federal law that allows them to restrict several types of material, including private communications between presidential advisers.

A memo written to Hillary Clinton in 1993, for example, is titled "Positioning ourselves on health care." A notice in the files says that archivists are withholding it on the ground its release would reveal confidential advice.

An undated 38-page memo also being sequestered is titled "General targeting strategy" - an apparent reference to the Clinton administration's targeting of members of Congress whose votes would have been needed to pass the plan.

In interviews, some people who were the focus of such memos said they were baffled about why the records were being held back.

Two 1993 memos kept private involve meetings between Hillary Clinton and then-Sen. Bob Kerrey (D., Neb.), who at the time opposed her health-care plan.

"It's hard to make the case that a meeting with Bob Kerrey in 1993 ought to be redacted, other than for political reasons," Kerrey said.

A three-page memo written to Clinton in 1993 involved a meeting with Rep. Jim Cooper (D., Tenn.), who was promoting an alternative to her health-care plan. That memo, too, is being withheld on the ground its release would disclose confidential advice. Cooper said in an interview: "I'm for open government. . . . Good, bad or indifferent, I want it out in the public."

A White House aide wrote a 130-page memo to Hillary Clinton in May 1993 about a meeting with Sen. Nancy Kassebaum (R., Kan.) and Rep. Dan Glickman (D., Kan.), who at the time were pushing an alternative health-care proposal. That memo is being withheld.

Glickman, in an interview, said he vaguely remembered the meeting. He voiced no objection to the memo's being publicly released, saying: "I don't think there was anything in the proposal that Sen. Kassebaum and I had that was particularly secret."

As they review records for release, archives staff rely on the Presidential Records Act, which says material may be withheld from the public on several grounds, including matters of national security and privacy.

A Clinton campaign spokesman said there was nothing she or Bill Clinton could do to alter the decisions of the National Archives and Records Administration on how quickly to release documents. Federal archivists move at their own pace and make their own decisions as to what should be withheld based on their reading of the law, said Jay Carson, a Clinton media aide.

The former president's involvement is limited, Carson said. When archivists are ready to release a batch of material, they notify a representative of Bill Clinton - longtime confidant Bruce Lindsey - who reviews it and decides whether to hold anything back. Lindsey has not suppressed anything, Carson said.

The archives staff, however, describes a more collaborative process. Before decisions are made on which memos to keep secret, archives staff may consult with Bill Clinton's representatives.

One archives official, who asked to speak on background because she is not the agency's formal spokeswoman, said that how legal restrictions governing memos between White House advisers "are eased and whether they are applied is up to the former president. . . . There is consultation."

Bill Clinton has given the archives guidelines on how to approach the task. In a letter sent in 2002, he said archivists should feel free to open up material that legally could be concealed on the ground that it involved federal appointments or communication between advisers.

But he said he did not want material released if it contained "negative" or "derogatory" information, if it centered on a "sensitive policy, personal or political matter," or if it involved "communications directly between the president and the first lady."

In addition to the health-care records, the William J. Clinton Presidential Library possesses two million pages of material from the former first lady's office; none has been released. Archivists have described their workload as so great that they don't expect the bulk of Hillary Clinton's records to be made public before the 2008 election.