Aromatic hydrazones and their derivatives are being explored to develop new drugs against microorganisms, resistant to presently available anti-microbials. In the present study, 13 hydrazone derivatives were screened in vitro for their biological activity against microorganisms by employing agar well diffusion method. The microbes, Escherichia coli, Staphylococcus aureus and Candida albicans were cultured on agar plates. Wells in agar plates were loaded with 50 μl of 0.02 μg/ml and 0.04 μg/ml of hydrazone derivatives. Biological activity was examined by measuring the zone of growth inhibition. Compounds, 5, 6 and 11 exhibited none or negligible zone of inhibition against S. aureus. Compounds, 1, 4, 7, 8, 10 and 12, showed moderate zones of inhibition. Compound, 13, was found effective against S. aureus. Against E. coli, the compounds, 5 and 8, showed no zone of inhibition; the compounds, 1, 2, 3, 4, 6, 7, 12 and 13, showed little zone of inhibition, whereas the compound 9 and 11, reflected moderate zone of inhibition. Compound, 10, was found to be the most effective. When these compounds were investigated against C. albicans, the compounds, 1, 2, 3, 4, 5, 7 and 10, showed little zone of inhibition; the compounds, 6, 8, 9, 11 and 12 ,exhibited moderate activity. Compound, 13, was found to be the most effective against C. albicans. Overall, hydrazone derivatives are very effective against microorganisms and should be evaluated against other microbes to determine their anti-microbial potential.