Affinity capillary electrophoresis of DNA was conducted in a poly(dimethylsiloxane)-glass hybrid microchip with a 100 gm (width) x 130mum (height) microchannel containing poly(N,N-dimethylacrylamide)-DNA conjugate. By this method, sample 12-mer oligonucleotide composed of c-K-ras codon 10-13 was separated from its single-base substituted mutant within 2 min.