The fabrication of mixed uranium-plutonium oxide fuel for the U.K. Fast Breeder Reactor Programme is discussed, and the experience gained by the United Kingdom Atomic Energy Authority and British Nuclear Fuels pic over the past 25 yr is used to identify aspects of the manufacturing routes that influence irradiation performance and subsequent recycle. The design of a small-scale production plant for fast reactor mixed-oxide (MOX) fuels is discussed, and its conversion to produce 8 tonne/yr (heavy metal) thermal MOX fuel is outlined.