Abstract: Petroleum ether, methanol and water extracts of Psidium guajava leaves were tested to determine their possible antimicrobial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative bacteria (E. coli and Salmonella typhi) and fungi (Aspergillus niger and Candida albicans). Each extract was used in concentration of 100, 50, 25 and 10%. Gram-positive and Gram-negative bacteria showed susceptibility toward all extracts, the zones of their inhibition ranged between (13-28 mm). Aspergillus niger showed complete resistance toward all extracts at all concentrations while Candida albicans was inhibited by water extract, all concentrations of petroleum ether extract and only concentration at 10% of methanol extract, the zones of inhibition ranged between (13-20 mm).