5-Fluorouridine 5'-O-β-D-galactopyranoside, also known as 5'-O-β-D-galactosyl-5-fluorouridine, is a prodrug of 5-Fluorouridine. 5-Fluorouridine 5'-O-β-D-galactopyranoside can be enzymatically converted by β-D-galactosidase into 5-Fluorouridine, which is a highly effective antineoplastic agent.