The growth of dislocation loops in Fe-15wt% Cr ferritic stainless steel was examined in the temperature range 200° ∼ 600°C using a high voltage electron microscope. At about 200°C black dots occurred in close proximity with one another and formed clusters. In the temperature range 300° ∼ 400°C small dislocation loops were formed and gathered into clusters of peculiar crystal orientations. Most of those loops lay on the {100} plane and were of the interstitial nature. Between 450° and 550°C, star-like dislocation loops grew, some of which formed the “pair.” Most of the loops existed on the {111} plane.