The synthesis and preliminary biological evaluation of a lipophilic, fluorine-18-labeled 5-ethynyl-2 0 -deoxyuridine derivative [18 F]-3 is described. Initially, 5-ethynyl-2 0 -deoxyuridine 5 was synthesized by coupling trimethylsilyl protected acetylene to 5-iodo-2 0 -deoxyuridine 4, followed by deprotection in alkaline conditions.Compound 5 was then reacted with 4-(4 F). The specific radioactivity of the tracer was between 74 and 222 GBq/mmol. The log P 7.4 of [18 F]-3 was found to be 2.4. However, biodistribution study in normal mice showed low uptake of the tracer in the brain. The affinity of compounds 6 and 3 for varicella-zoster virus thymidine kinase enzyme (VZV-TK) was examined in vitro and the results revealed that the fluorinated analog 3 has a poor affinity for the enzyme in contrast to the phenol precursor 6.