Regulatory Improvement Act of 2000 - Requires a Federal agency, when it publishes a notice of proposed rule making for a major rule, to: (1) prepare and place in the rule making file an initial regulatory impact analysis; and (2) include a summary of such analysis in the notice of proposed rule making.

Requires that, when the Director of the Office of Management and Budget has designated a rule as a major rule, or when an agency has published an interim final major rule, such agency shall: (1) promptly prepare and place in the rule making file an initial regulatory impact analysis; (2) publish in the Federal Register a summary of such analysis; and (3) give interested parties the same opportunity to comment as if the initial regulatory impact analysis had been issued with the notice of proposed rule making. Requires an agency publishing a final major rule to prepare and place in the rule making file a final regulatory impact analysis which shall reflect any changes made to the proposed rule or its cost-benefit analysis or risk assessment, as well as agency consideration of comments from interested parties as provided above.

Mandates a comparative risk study by the Director of the extent and severity of significant risks to human health, safety, or the environment. Requires the President to periodically report to Congress recommending legislation to reduce such risks.