This study investigated the antimicrobial activity of crude and fatty acids extract of nine marine macroalgal species (Caulerpa racemosa, Ulva fasciata, Halimeda tuna, Galaxura rugosa, Hypnea cornuta, Jania rubens, Tu rbinaria tubinata, Hormophysa cuneiformis and Polycladia myrica). The antibacterial activity of these extracts was assayed against Bacillus Subtilis, Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus, while the antifungal activity was achieved against Aspergillus niger and Candida albicans. The fatty acid macroalgal extracts recorded the highest antimicrobial activities against Bacillus Subtilis, Staphylococcus aureus and Candida albicans compared to the crude macroalgal extracts. Most of the brown macroalgae extracts exhibited significant antimicrobial activity against the tested bacteria and fungi. The crude and fatty acid extracts of the selected macroalgae species showed no inhibition zones against Aspergillus niger. Caulerpa racemosa, Hypnea cornuta Turbinaria tubinata and Hormophysa cuneiformis showed antimicrobial activity against all the tested pathogenic microorganisms. The brown macroalga Polycladia myrica recorded the maximum inhibition zone. The fatty acids extract of the brown alga Hormophysa cuneiformis and the red alga Jania rubens recorded the highest inhibition zones against the fungus Candida albicans. This study established that the macroalgal fatty acids extracts were highly effective against the pathogenic bacteria and fungi than the crude macroalgal extract as well as the standard commercial antibiotic. The marine macroalgae can be used as a potential source for natural pharmaceutical products against the infectious diseases.