This paper describes the chemical synthesis of a chain-branched, monosaccharide nitrosamine: 3-[N-nitroso-N-ethyl]-aminomethyl-D-allose. Nitrosamines with alpha-carbon-carbon-bonded carbohydrate residues (hydrophilic carrier) could be interesting for experimental cancer research; specifically, in biological experiments (testing for carcinogenic, mutagenic or teratogenic effects), biochemical experiments (enzymatic activation, metabolites) and physiological experiments (resorption studies).