A method for an ultrasensitive silver-based color staining of proteins described by Sammons et al. was applied to the detection of oligonucleotides on polyacrylamide gels with slight modifications in the method of fixation. With these modifications, we can stain even tetranucleotide bands such as dA₄. Furthermore, the sensitivity of staining of Hae III fragments of φX 174 RF DNA is several times higher than with ethydium bromide staining. The sensitivity of this silver-staining differs markedly among various homo-oligonucleotides. The limit of detection of rA₁₀ or dA₁₀ is approximately 40pg per mm² of cross-sectional area. Homo-oligonucleotides, dG₁₀ and dC₁₀, are also detectable. However, the dT₁₀ band concentrated more than 1, 000-fold could not be detected on the polyacrylamide gel by silver staining. Thus, the silver staining method is very useful for the sensitive detection of oligonucleotides as short as tetranucleotides that are not stained by ethidium bromide.