The genus, Hymenocrater, belongs to the plant family Lamiaceae which contains eleven shrub species, of which H. calycinus belonges and grows wildly in Northeastern Iran. From the ethyl acetate and methanol extracts of the flowered aerial parts of Hymenocrater calycinus, four compounds were isolated using chromatographic methods and identified by spectroscopic data (MS, 1 H-and 13 C-NMR, HMQC, HMBC and 1 H-1 H COSY). The effect of rosmarinic acid, as the main component in our study was applied to Staphylococcus aureus, Escherichia coli, Candida albicans and Aspergillus niger by the broth dilution method. Isolated compounds were identified as ß-sitosterol (1), ursolic acid (2), rosmarinic acid (3) and quercetin-3-O-rutinoside (4). The results of our assay against bacteria and fungi show that, rosmarinic acid has an antifungal property against Candida albicans (MIC, 250 μg mL -1 ).