A series of 5′‐deoxy‐5′‐hydroxylamino derivatives of adenosine and uridine have been prepared by reduction of the corresponding oxime or nitrone. ‘Second generation’ 3′‐deoxy‐3′‐N‐aryl(or N ‐alkyl) hydroxylamino‐β ‐ D‐xylofuranosyluracils have also been synthesized by a one‐pot reaction including the following elementary steps: deblocking of the starting material, reduction of the 3′‐deoxy‐3′‐oximinouridine, condensation of the resulting hydroxylamine with an aldehyde, reduction of the nitrone formed. The deoxy-hydroxylaminonucleosides oxidized spontaneously in the air (or in presence of traces of PbO₂) to give the corresponding nitroxide free radicals, ESR spectra of which furnished useful informations on their structures. Some of these modified nucleosides bore notable cytotoxic or antiviral activities.