1. The effects of vanadium ions on the .OH radical production in the presence of and in the absence of dialuric acid were studied. 2. Dialuric acid enhanced deoxyribose degradation. 3. Vanadium ions and vanadium/EDTA complexes decreased the degradation of deoxyribose in the presence and in the absence of dialuric acid. 4. The question as to whether or not free .OH radicals are formed via reaction of vanadium ions with H2O2 in the presence of dialuric acid is discussed. 5. The results are interpreted with a view to the vanadium ability to decrease the toxic effects of dialuric acid.