Self-ion implanted molybdenum has been annealedin situin the transmission electron microscope at temperatures up to 1000°C. At low temperatures, ∼500°C, microcrystallites are nucleated on the heavily damaged surface of the foil. The microcrystallites undergo limited growth before being consumed by growth of the underlying matrix. The later stages of annealing consist of the annihilation of point and line defects by normal, thermally-activated mechanisms. Grain boundary re-orientation has also been observed.