Separations of twenty phenylthiohydantoin (PTH) amino acids, and amino acid derivatives, resulting from the Edman degradation of peptides and proteins, were optimized for peptide sequencing by capillary electrophoresis. Manual sequencing of angiotensin II was performed by Edman degradation and capillary electrophoresis of the PTH amino acid obtained after each cycle. The results were compared with those of an automated conventional protein sequencer. Interfacing capillary electrophoresis with Edman degradation provides an additional option for protein sequencing.