21st Century Health Information Act of 2005

21st Century Health Information Act of 2005 - Authorizes the Secretary of Health and Human Services to make grants to regional health information organizations to develop and implement regional health information technology plans.

Requires the Director of the Agency for Healthcare Research and Quality (AHRQ) to establish and maintain a national technical assistance center to provide assistance to physicians to facilitate adoption of health information technologies and participation in such regional plans.

Requires the Secretary to establish a program of accrediting health information networks.

Requires the Comptroller General to report to Congress on the progress of regional health information organizations in realizing the purposes of this Act.

Prohibits federal funds available under this Act from being used for the purchase of a health information technology product unless such product has been certified as incorporating interoperability data standards and compliance criteria.

Allows the Secretary to make loans to any accredited regional health information organization to finance investments in network infrastructure and technology acquisition, training, and workflow engineering for physicians.

Amends the Social Security Act to exclude the provision of equipment or services for the development of such a regional plan from illegal remuneration provisions and limitations on physician compensation arrangements.

Requires the Secretary to: (1) establish a methodology for making adjustments in Medicare payments to providers participating in an accredited network; and (2) make matching Medicaid payments to states for the development and implementation of a regional plan under certain circumstances.