In this study, extracts obtained from Primula longipes Freyn and Sint plant are reported to have antiviral effects against Autographa californica nuclear polyhedrosis virus, a baculovirus, in cell culture. We have assessed the antiviral activity of extracts prepared in ethanol. The used concentrations of root and stem extracts obtained from P. longipes plant were 200 mug/mL, whereas, the used concentration of leaf extract was 20 mug/mL. We determined that extract obtained from leaf has higher antiviral effect, and it causes 66% decrease of the virus concentration. The results suggest that a major mechanism of inhibition of baculovirus infection by Primula extracts is through interference with gene expression.