Starting from 2′,5′-di-O-TBDMS-3′-ketouridine 1 or its thymine analogue 2, both xylo (3–10) and ribo (20) epimers of a series of 3″-substituted 3′-spironucleosides have been obtained in good yields and with a total stereoselectivity. Most new compounds were moderately cytotoxic with in some cases slightly selective antiproliferative activities. None of these compounds was active against HIV, but some other antiviral activities against HSV-2, CMV, EBV, or VZV, in the micromolar range, were noted in specific cases.