Capillary zone electrophoresis and carrier ampholytes based capillary electrophoresis have been used as a second separation step to Off-Gel isoelectric focusing for the analysis of complex peptide mixtures. A tryptic digest of four proteins (bovine serum albumin, beta-lactoglobulin, horse myoglobin, cytochrome c) has been chosen as a peptide test mixture. After assessment of different modes of capillary electrophoresis as a second dimension to Off-Gel isoelectric focusing, the optimized two-dimensional platforms provide a degree of orthogonality comparable to state-of-the-art multidimensional liquid chromatography systems as well as a practical peak capacity above 700.