Background & Aim: Nowadays, the application of traditional medicine and herbal medicinal plants instead of chemical and synthetic drugs has captured the attention of the researchers. The purpose of this study was to investigate the antimicrobial effects of the aquatic, ethanolic and methanolic (80%) extracts of the aerial and root parts of Stachys lavandulifolia Vahl which were taken from the countryside of Marand (Eastern Azerbaijan, Iran) in two generative and vegetative phases against standard strains of microorganisms. Experimental: Antimicrobial activity of the alcoholic and aquatic extracts from different parts of S. lavandulifolia was investigated against standard strains of Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027) through well-plate and micro-dilution methods. Ampicillin as antibacterial agent was used as positive control. Results & Discussion: Results of antimicrobial properties of S. lavandulifolia extracts revealed that the aquatic extract of the plant had no antibacterial effects. While the ethanolic and methanolic (80%) extracts showed the growth inhibition effect against standard strains of examined microorganisms. Their effect against Gram-positive bacteria was higher than Gram-negative bacteria. The antimicrobial activity of the ethanolic extract from the inflorescence of S. lavandulifolia was higher than the alcoholic extract of the roots. Recommended applications/industries: The overall results indicated the ethanolic extract of the inflorescence of Stachys lavandulifolia has the best antimicrobial effects and it can be employed in manufacturing desirable bactericidal agents. تفاصيل المقالة