The 2'-substituted-4'-selenoribofuranosyl pyrimidines 3a-3j were synthesized from D-ribose and assayed for anticancer activity. The 2'-azido and 2'-fluoro groups with a ribo configuration were introduced by the regioselective opening of the O2,2'-anhydronucleosides with sodium azide and (HF)x-pyridine, respectively. Among the compounds tested, only 2'-fluoro derivative 3j was found to exhibit significant anticancer activity, but was much less potent than the corresponding 2'-arabino analogue 2c. This study will provide medicinal chemists with the insight into the identification of structural requirements for the anticancer activity for the developments of biologically active nucleosides.