The American Forces Press Service says Kiley resigned his post as Army surgeon general on Sunday. Kiley also served as commanding general of the Army Medical Command.
Acting Army Secretary Pete Geren asked for Kiley's resignation, CNN said. Kiley said his retirement is "in the best interest of the Army," according to a Pentagon statement.
Kiley's resignation follows Secretary of the Army Francis Harvey's March 2 resignation.
Maj. Gen. Gale Pollock, currently serving as deputy surgeon general, will assume Harvey's duties while a replacement is sought. A replacement will require approval by the president and confirmation by the Senate.
President Bush has appointed former Senate Majority Leader Bob Dole and former Clinton administration Health Secretary Donna Shalala to head a panel on how to care for those wounded in Iraq and Afghanistan. CNN says the panel's report is due June 30.