Cytotoxic, antiviral, antibacterial and antifungal properties of a new, originally synthesised group of compounds: the N-benzoylphenylisoserinates of sesquiterpenoid alcohols - derivatives of taxol and various sesquiterpenes of Lactarius origin were evaluated in vitro. Among 16 compounds tested, 6 decreased HSV-1 titres. Selectivity indices ranged from 13.9 to 31.7. No activity against RNA viruses (parainfluenza 3, Coxsackie B3, vesicular stomatitis virus, and encephalomyocarditis virus), bacteria: Escherichia coli, Proteus mirabilis, Staphylococcus aureus, Enterococcus faecium and Bacteroides fragilis and fungal strain of Candida albicans was detected.