Carrichtera annua a plant belonging to family Brassicaceae was selected to be evaluated for its antimicrobial activity against a number of microorganisms. The powdered plant was extracted with ethanol until exhaustion. The concentrated ethanol extract was tested against a number of fungi, gram positive and gram-negative bacteria. The results revealed that the extract showed a significant and promising activity towards Aspergillus fumigatus, Proteus vulgaris, Enterococcus faecalis and Staphylococcus aureus with inhibition zones equal 17, 15, 13 and 11 mm. respectively. However, it displayed a weak activity on Bacillus subtilis and Klebsiella pneumonia. In contrast, the extract was inactive against Candida albicans, Trichophyton rubrum, Bacillus cereus, Methicillin-Resistant Staphylococcus aureus (MRSA), Salmonella typhimurium, Escherichia coli and Pseudomonas aeruginosa. Additionally, the minimum inhibitory concentration (MIC) was determined and illustrated that, the most susceptible organisms to C. annua were Aspergillus fumigatus and Proteus vulgaris with MIC of 2.5 mg/mL and 5 mg/mL respectively. Therefore, C. annua could be considered as a promising source for effective antimicrobial agent.