A reconstituted mixture of five cross-linked dinucleosides possibly involved in DNA-nitrosourea interactions, and of their degradation products (nucleobases, deoxynucleosides and mono- or disubstituted deoxynucleosides), was analysed by reversed-phase high-performance liquid chromatography using C18 columns and an diode-array detector. The chromatographic conditions for separating the twenty-one investigated compounds were optimized, and the compounds were identified by both their retention times and their UV spectra. A structure-retention time relationship was observed under suitable conditions and is discussed. Its validity was confirmed by the prediction of the retention time of a new cross-linked dinucleoside synthesized for this purpose.