SYNOPSISUsing a factor analysis technique, the experimental physicochemical data on the hydration of mononucleotides, several polynucleotides, their double-helical complexes and natural DNAs were studied. The information about the factors determining the changes in physicochemical parameters vs the hydration was obtained. This work discusses a possible physical sense of the factors obtained and the expedience of using factor analysis to interpret the molecular-biophysical experiments