Abstract Essential oils were isolated from the aerial parts during the flowering and vegetative phases, roots and seeds of the plant Portenschlagiella ramosissima and their antimicrobial activities against bacteria (Salmonella enteritidis, Escherichia coli, Micrococcus flavus, Bacillus subtilis, Staphylococcus aureus) and micromycetes (Aspergillus flavus, A. niger, A. versicolor, A. ochrachloron, Penicillium funiculosum, Trichoderma viride) were tested. Among tested bacterial and fungal species were plant pathogens, food poisoning species, animal and human pathogens. The main component in all oils samples was myristicin (61.1â91.5 %). Antimicrobial activity of oils was tested using the micro-dilution and disc-diffusion methods. All of the oils tested showed activity.