||Goal: Overview of use of medical herbs and their anti – bacterial affect using known literature and personal research. Research objectives: 1. Analyze and asses calendula antibacterial effect. 2. Analyze and asses thyme antibacterial effect. 3. Analyze and asses oregano antibacterial effect. 4. Analyze and asses sage antibacterial effect. 5. Analyze and asses Iceland Moss antibacterial effect. Thesis conclusions: 1. Sprit based medicinal plant extracts had a significantly stronger effect on bacteria than water based ones. Spirit and water based extracts had stronger effect on Gram-positive bacteria than Gram-negative ones. Higher concentrations plant extracts (100 mg / ml) had stronger effect than the lower (50 mg / ml) counterparts. 2. Water and ethanol based calendula extract at 100 mg / ml concentration had the strongest effect against Gram positive bacteria (inhibition zone of 10.8 ± 1.8 mm to 18.4 ± 1.6 mm) least effective was Pseudomonas aeruginosa (inhibition zone of 8.7 ± 1.2 mm to 11.3 ± 2.2 mm). 3. The plates were gram-positive bacteria were cultivated had the highest thyme inhibition zone (from 16.5 ± 2.7 mm to 26.1 ± 2.6 mm), while escherichia and Pseudomonas had lower inhibition zone (from 11.2 ± 1.4 mm to 13.1 ± 2.3 mm). 4. 100 mg /ml spirit extract of oregano was strongest against staphylococci (inhibition zone of 22.1 ± 2.8 mm) and least strong on pseudomonas (9.6 ± 1.7 mm). Sufficient inhibition zone occurred when water based extract concentration was 100 mg / ml on most of Petri plates (with the exception of Pseudomonas aeruginosa). 5. Larger than 10 mm inhibition zone for 100 mg / ml water based sage extract was measured in plates, that had been seeded with staphylococci, enterococci, E. coli, and klebsiella while 100 mg / ml spirit extract was equally effective on all bacteria. 6. Water based Iceland moss extract had no or little effect on all bacteria. Only 100 mg / ml spirit based moss extract had anti-bacterial effect against Gram-positive microorganisms (inhibition zone of 13.7 to 15.4 mm), but had little effect on Gram-negative bacteria (5.8 to 7.3 mm inhibition zone).