Eight new D-1.3-dioxolanyl and L-1,3-oxathiolanyl nucleosides containing 5-phenyl- selenyl pyrimidine bases which are expected to have antiviral activity were synthesized. Condensation of D-1,3-dioxolane acetate and L-1,3-oxathiolane acetate with 5-phenylselenyl pyrimidines gave anomeric mixtures of their nucleosides which were separated by silicagel column chromatography.