Helichrysum litoreum Guss, a Campania medicinal plant reported to have antibacterial properties, was evaluated for antiviral activity against herpes simplex virus type 1 (HSV-1) in vitro. The crude aqueous extract from leaves of Helichrysum litoreum at a concentration of 1.35 mg/ml (ww/v) showed significant antiviral activity on HSV-1 in human lung fibroblast as demonstrated by the absence of a cytopathic effect.