Present methods for sequence analysis of ribooligonucleotides [ 1,2] fall into two major groups: those based on the sequential o-elimination of 3’-terminal nucleotides [3-161 and those which use a combination of specific endonuclease cleavage and controlled exonuclease digestion [ 171 . Although o-elimination provides a method for sequencing RNA that cannot readily be labelled biologically to high specific activity, the eliminated nucleoside methylene dialdehydes are unstable. The other method has found wide application in sequence studies on uniformly 32P-labelled RNA, but it requires the isolation and characterization of many oligonucleotides of shorter chain length than the initial polynucleotide. were isolated from a fingerprint [ 18,201 of a ribonuclease T1 digest of unlabelled Cowpea Chlorotic Mottle Virus RNA. (The pentanucleotide is No. 14; the tetranucleotide is No. 12 and the trinucleotide is No. 11 on the fingerprint.) All the oligonucleotides were in unbuffered aqueous solution. In order to correlate the results, it was found best to perform the following experiments at the same time using equal amounts of the oligonucleotide.