A three-step synthesis of [2-11C]thymidine, using [11C]urea as precursor, is described. [2-11C]Thymine was obtained by cyclization of [11C]urea and diethyl beta-methylmalate in fuming sulfuric acid. After purification of the reaction mixture, [2-11C]thymine and 2'-deoxyribose-1-phosphate were incubated in the presence of thymidine phosphorylase to form [2-11C]thymidine. The whole synthesis procedure, including purification and pharmaceutical package, was achieved within 60 min with a decay corrected yield of 30-35%.