Uranium resources continue to be an important concern in assessing energy options and strategies. The question of the uranium supply for the development of nuclear power has also become one of the major focal points in the controversy over the breeder reactor program and nuclear fission energy in general. World reserves at a cutoff cost of production up to $15/lb of U3O8 are ∼1.1 million MTU, and the estimate of undiscovered potential resources ∼1.7 million MT. Exploration throughout the world has not yet identified significant numbers of new types of uranium deposits that might begin to fill the apparent gap between long-term demand and supply; that is, large intermediate-grade deposits containing 100 to 700 ppm uranium. In 1973 the U.S. Atomic Energy Commission initiated an accelerated and expanded resource evaluation program to ascertain the total U.S. uranium resource base, including the potential of areas largely ignored in past exploration. Preliminary investigations to date have indicated additional potential resources in the possible and speculative categories of ∼850 000 MT at a production cutoff cost of up to $30/lb. It is unlikely, however, that the annual production of ∼100 000 MT projected by the year 2000 could be achieved from the presently estimated resource base of 2.7 million MT—reserves plus potential—80% of which remains to be found. Thus, information to date continues to support the need for the early introduction of the breeder reactor.