Peroxisomes were visualized for the first time in living fission yeast cells. In small, newly divided cells, the number of peroxisomes was low but increased in parallel with the increase in cell length/volume that accompanies cell cycle progression. In cells grown in oleic acid, both the size and the number of peroxisomes increased. The peroxisomal inventory of cells lacking the dynamin-related proteins Dnm1 or Vps1 was similar to that in wild type. By contrast, cells of the double mutant dnm1Delta vps1Delta contained either no peroxisomes at all or a small number of morphologically aberrant organelles. Peroxisomes exhibited either local Brownian movement or longer-range linear displacements, which continued in the absence of either microtubules or actin filaments. On the contrary, directed peroxisome motility appeared to occur in association with mitochondria and may be an indirect function of intrinsic mitochondrial dynamics. We conclude that peroxisomes are present in fission yeast and that Dnm1 and Vps1 act redundantly in peroxisome biogenesis, which is under cell cycle control. Peroxisome movement is independent of the cytoskeleton but is coupled to mitochondrial dynamics.