Abstract Some halogenated isopentyl phenols were synthesized and screened for possible antibacterial and antifungal activities against Staphylococcus aureus, Streptococcus viridans, Escherichia coli, Shigella flexneri, Salmonella typhi, Salmonella typhimurium, B.proteus vulgaris, Pseudomonas aeruginosa, Bacterium antracoides, Bacterium subtilis, Klebsiella rhinoscleuromatis and Candida albicans using the microdilution method. Antimicrobial tests results indicated that all compounds have reasonable activity. They displayed the highest antimicrobial activity against Streptococcus aureus, Streptococcus viridans and Candida albicans. The isopentyl phenols containing chlorine atoms were the most active than the fluorine containing phenols in the series against majority tested bacteria and fungi strains.