Separations of five synthetic heptadecapeptides from the p-loop region of p21 Ras proteins, differing mostly in a single amino acid at the same position, were investigated. The studies were performed at low pHs in polyacryamide-coated capillaries, where the peptides were slightly positively charged. CZE, without surfactants, failed to separate all the peptides. Separations by MEKC employing an anionic surfactant sodium dodecyl sulfate (SDS), a neutral surfactant Tween 20 and a cationic surfactant cetyltrimethylammonium bromide (CTAB) provided results with varying degrees of success. Tween 20, slightly improved the separation while CTAB resulted in almost baseline separation of all the peptides.