Twenty kinds of alpha-amino acids were directly detected by capillary electrophoresis (CE) with a chemiluminescence (CL) detector using luminol-hydrogen peroxide-Cu(II) system. A batch-type CL detection cell to which a hydrogen peroxide solution was added was used. Samples migrated in a running buffer solution containing luminol and Cu(II), and eluted at a tip of a capillary to mix with the hydrogen peroxide. The catalytic activity of Cu(II) for luminol CL reaction increased in the presence of a-amino acids to induce CL peaks on the electropherograms. For example, aspartic acid was determined over the range of 1.1 x 10(-7)-1.8 x 10(-5) M with a detection limit of 0.6 fmol. A model mixture sample of glycine, aspartic acid, and glutamic acid was successfully separated and detected within 10 min.