In the factory of pharmaceutical and chemical products, "Zdravlje", Leskovac, in collaboration with Faculty of Technology, Leskovac, antimicrobial and chemical examinations of the plant species belonging to genus Hypericum L. have been carried out.

The aim of this work is comparison of antimicrobial characteristics of the following species: Hypericum maculatum Crantz., Hypericum rumelicum Boiss., Hypericum perforatum L., Hypericum olympicum L. The examinations were carried out by means of diffuse method on the cellulose disc, according to Ph. Jug. IV, using 10 following test microorganisms: Bacillus subtilis S, Escherichia coli 95, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus ATCC 6538, Sarcina lutea 9341, Salmonella enteritidis, Aspergillus niger, Candida albicans ATCC 24493 and Sacharomyces cerevisiae ATCC 9763.

On the basis of the obtained results it can be concluded that all examined plant species showed an outstanding antimicrobial effect. The greatest antimicrobial activity was shown by Hypericum olympicum L.