The ethanol extracts obtained from Ballota acetabulosa (L.) Benth (Lamiaceae) were investigated for their antimicrobial activity against Bacillus cereus ATCC 7064, Bacillus subtilis ATCC 6633, Stapylococcus aureus ATCC 6538P, Escherichia coli ATCC 10538, Proteus vulgaris ATCC 6899, Salmonella typhimurium CCM 5445, Psuedomonas aeruginosa ATCC 27853, Debaryomyces hansenii DSM 70238, Kluyveromyces fragilis ATCC 8608 and Rhodotorula rubra DSM 70403 by disc diffusion method and micro dilution method. The extracts showed strong antibacterial activity against E. coli, with inhibition zones of 18.6 mm and with minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of 16 (32) mu g/mL, respectively. K. fragilis is among the most susceptible in the yeast cultures, with inhibition zone of 18.2 mm and with MICs and minimum fungicidal concentrations (MFCs) of 16 (32) mu g/mL, respectively. Also, the extracts exhibited moderate activity in the other test of micro-organisms. The results demonstrate that the ethanol extract of the aerial parts of B. acetabulosa has significant activity and suggest that it may be useful in the treatment of infections.