Main antibacterially active agents obtained from plants-Cajeput essential oil--1,8 cineol, linalool, alpha-terpineol and terpinen-4-ol, for example from Melalleuce leucadendron (Myrtaceae) as well as essential oil from Ocimum gratissimum (Labiatae) were combined in tests in vitro with selected antibiotics. Above mentioned plant products were found to be effective medicaments for local application in modern medical practice. Combinations with antibiotics potentiated their therapeutical action. On the basis of tests in vitro the synergistic action of these two kinds of medicaments, i.e., preparations traditionally used for a few last decades--antibiotics--might be well applied for therapeutical needs.