Approximately one-third of all proteins reported in the literature have a pI sufficiently high to be resolved by cation-exchange chromatography. This paper reports the preparation and use of new high-performance polymeric-bonded-phase cation-exchange columns. Starting from a very stable, covalently bonded polyamide coating on microparticulate silica, simple derivatization produces a versatile cation-exchange material useful for separations traditionally performed on classical carboxymethylated soft gel supports. Column behavior was monitored using chymotrypsinogen, cytochrome c, and lysozyme as standards. The polymeric bonded phase was stable to pH 2.5 and exhibits enhanced selectivity for proteins due to a slight hydrophobic character of the matrix. Several separations of biological interest that demonstrate the utility of these small cation-exchange columns for modern biochemical separations are shown.