Essential oil of Vitex agnus-castus' leaves was analysed GC and GC-MS. The oil was predominantly rich in 1,8-cineole (24.38 %), sabinene (22.77 %), trans--farnesene (8.50 %), -pinene (7.14 %), -caryophyllene (6.49 %) and 1-terpinen-4-ol (5.23 %). In the phytotoxicity assay, the highest concentration of the oil (40 mu L) completely inhibited the germinations of Lactuca sativa and Lepidium sativum. In the antimicrobial assays, essential oil was more active on yeast species and gram positive bacteria. The results of the insecticidal assays were also significant as the mortalities were 70 % and 96.67 % on Acanthoscelides obtectus and Tribolium castaneum at 34 mu L L-1 and 136 mu L L-1 oil (24h), respectively. Essential oil of V. agnus-castus could be suggested as a potential source of bioagents for prokaryotic and eukaryotic organisms in concern.