Radioprotectant Procurement Act of 2005 - Amends the Homeland Security Act of 2002 to direct the Secretaries of Health and Human Services, Homeland Security, and Defense to utilize and expend funds necessary for rapidly developing, bringing to market, and procuring whole-body radioprotectants.
Requires the Secretary of Homeland Security: (1) to report to Congress on the threat of a nuclear or radiological attack against the United States and the availability of effective radioprotectant medical countermeasures; and (2) upon determining that an effective radioprotectant is available or may become available within a reasonable time, to enter into agreements with private companies for the procurement of enough effective, safe, stable, and low-cost radioprotectants to protect the people of the United States.