Thymidine is a pyrimidine 2'-deoxyribonucleoside having thymine as the nucleobase. It has a role as a metabolite, a human metabolite, an Escherichia coli metabolite and a mouse metabolite. It derives from a thymine. It is an enantiomer of a telbivudine.It is used as a pharmaceutical intermediate for the synthesis of antiviral and anti HIV drugs.