The ability to control plant viral diseases with chemicals has great potential value for agriculture, but few chemicals are available to date due to the difficulty in obtaining effective drugs. IMP dehydrogenase is an enzyme which catalyzes the conversion of inosine 5′-monophosphate to xanthosine 5′-monophosphate in the de novo purine nucleotide synthetic pathway, and is considered a sensitive target for antiviral drugs. Two IMPDH inhibitors, tiazofurin (TR) and mycophenolic acid (MPA), were tested for their inhibitory effect on Grapevine leafroll-associated virus 3 (GLRaV-3) in in vitro grapevine explants. TR administration produced plantlets characterized by negative ELISA readings. No PCR products were obtained from these samples. This was confirmed by the absence of viral particles. MPA was essentially ineffective against GLRaV-3 replication in Sangiovese explants. This is the first report of GLRaV-3 eradication in grapevine explants following TR administration.