Peptides derived from digestion of 1 mumol of sunflower cytochrome c with chymotrypsin were separated by paper electrophoresis. The sequences of these peptides were determined by using the dansyl-Edman method (Gray & Hartley, 1963) and confirmed by analysis of their amino acid composition. Comparison of the set of peptides with the chymotryptic peptides of mung-bean (Thompson, Laycock, Ramshaw & Boulter, 1970) and wheat germ (Stevens, Glazer & Smith, 1967) cytochrome c shows a clear homology. The complete sequence of sunflower cytochrome c was established by alignment of the sunflower peptides with the sequences of mung bean cytochrome c and wheat germ cytochrome c.