A total of 10 reversed-phase columns obtained from different suppliers were evaluated for their ability to separate typical peptide mixtures: tryptic digests of cytochrome c, lysozyme and collagen. Each column was tested in a standard gradient elution using phosphate buffer (pH 2.85) as the A-solvent and acetonitrile as the B-solvent. Some differences in band spacing for the various peptides were observed from column to column. More important differences were observed in the ability of these various columns to provide narrow peaks and good resolution, as measured by column peak capacity. These differences in column peak capacity were related to differences in column dimensions and particle size; it also appeared that C8 bonded phases were somewhat more efficient than were C18 phases. The recovery of cytochrome c digest from four of the columns was also assessed. Summed peak areas were proportional to sample size, as the latter was varied from 1 to 100 micrograms. The apparent recovery from each column did not vary by more than +/- 5%. From this it was concluded that these columns gave essentially quantitative recovery for this particular sample. Limited data on column life were obtained for some of these columns.