Our objective was to determine whether quantitative polymerase chain reaction (PCR) can be used to measure the effect of tyrosine kinase (TK) inhibition on polyomavirus BK (BKV) replication. The BKV was grown in a cell culture system. The rate of viral replication in the presence or absence of the drug being tested was assessed by amplifying the viral genome using primers directed against the viral capsid 1 protein. Dasatinib, erlotinib, gefitinib, imatinib, sunitinib, and sorafenib all showed antiviral activity at micromolar concentrations. The 50% effective concentration for erlotinib and sorafenib was within blood concentrations readily achieved in human subjects. Quantitative PCR is a convenient method for viral drug sensitivity testing for slow-growing viruses that do not readily produce cytopathic effect. TK inhibitors deserve further consideration as a potential therapeutic option for BKV-associated nephropathy and hemorrhagic cystitis.