The US National Institutes of Health (NIH) has unveiled its long-awaited plan for open access to research findings. Elias Zerhouni, the NIH's director, claimed at a public briefing on 3 February that the plan could “change the landscape” of biomedical publishing.

The policy requests that authors whose research was funded by the NIH submit copies of their papers to the agency's National Library of Medicine after they are accepted for publication. The papers will then be placed in an online archive. Authors can decide when their papers are made available to the public, but the NIH would like this to happen as soon as possible, and in any case within 12 months of publication.

Scientists pushing for open access have praised the policy, which comes into effect on 2 May. “This is a significant and positive step and I'm glad we have the policy written down,” says Harold Varmus, president of the Memorial Sloan-Kettering Cancer Center in New York.

But both sides of the debate have voiced criticism. Advocates of full open access are unhappy that the policy is voluntary and does not require access within six months of publication — a deadline that Zerhouni had proposed in a draft version (Science 306, 1895; 2004).

“This is a retreat from the earlier version of the policy, and the retreat is unjustified and regrettable,” says Peter Suber, director of the Open Access Project at Public Knowledge, a non-profit advocacy group in Washington DC.

Suber and other critics say it would put researchers in the difficult position of having to negotiate between the NIH, which wants work available as soon as possible, and journals, which may want researchers to wait.

Publishers and societies that draw income from publishing criticize the NIH's plan to archive papers on its own site instead of directing the public to journal websites. NIH officials estimate that it will cost between $2 million and $4 million a year to run.

“The NIH is proposing to create a new publishing enterprise, and it's going to have to spend a lot of money to do that,” says Marc Brodsky, chief executive of the American Institute of Physics.

Zerhouni said the announcement, expected on 11 January, had been delayed at the request of the health department and the White House.