In the γ-radiolyse of N2O saturated aqueous solutions of 2-deoxy-D-ribose (8·10-3 mol/l) the following products (G-values) are formed: 2-deoxy-ᴅ-erythro-pentonic acid (and its γ-lacton) (1) (2,5), 2.5-dideoxy-ᴅ-erythro-pentonic acid (8) (0.63), 2-hydroxy-oxa-cyclohexanone-(4) (5) (1,15), 2-hydroxy-oxa-cyclohexanone- (5) (6) (1,0), 3-hydroxyglutaraldehyde (7) (0,55), further, α-hydroxy-carbonyl compounds 2-4 (0,2) and possibly malonaldehyde (≦ 0,1). The formation of the products can be explained by the attack of the water radicals (˙OH and ˙H) on the 2-deoxy-ᴅ-ribose to give primarily 2-deoxyribosyl radicals. These radicals may disproportionate directly, rearrange or eliminate water analogous to those from ethylene glycol1. The main product 1 stems from a disproportionation reaction of primary 2-deoxyribosyl radicals, 8 has a rearranged radical as a precursor, while in the formation of 5-7 primary 2-deoxyribosyl radicals split off water before disproportionation. The mechanism are discussed in detail