A relatively simple silver stain which takes less than 15 min to perform has been developed for the detection of nanogram quantities of proteins and DNA on cellulose membranes and thin layer plates. This stain demonstrates a reproducible curvilinear relationship between silver density and the amount of protein or DNA, over an averaged concentration range from 1 to 300 ng for proteins and 10 to 710 ng for DNA. The ease of staining proteins and DNA on membranes, combined with the stain's sensitivity and reproducibility, permits the use of this procedure for the quantitative determination of nanogram amounts of proteins and DNA. The simplicity of this silver stain has also permitted a survey of the staining properties of individual amino acids, purine and pyrimidine bases, nucleosides, nucleotides, homopolymers, and small peptides of known sequence. This survey demonstrated the importance of the basic amino acids, particularly lysine and histidine, and the sulfur-containing amino acids in the detection of proteins. It also indicated that the purine bases may play an important role in the detection of DNA.