The present study aimed to evaluate the antimicrobial activity (against selected bacterial, fungal and yeast strains) of successive extracts from different blue green algae. Aqueous and organic extracts of seven cyanobacterial species were screened against in vitro eight human bacterial pathogens and five fungal strains. Chloroform extract of the seven cyanobacterial species showed largest antibacterial inhibition zone diameter against the pathogenic bacterial strains. The chloroform extracts showed a broad spectrum against Gram- negative bacteria (Escherichia coli, Aeromonas hydrophila, Salmonella enterica S 1180, Klebsiella pneumonia K 51, Vibrio cholera V116 and Salmonella paratyphi) and Gram-positive bacteria (Staphylococcus aureus S 1426, Listeria monocytogenes L 49). However, the chloroformic extracts displayed also antifungal activity against Aspergillus terreus F98, while, none of the extracts of the seven cyanobacterial species demonstrated any activity against Tirchoderma viride F94. Meanwhile, the ethanolic extracts of four of cyanobacterial species showed antifungal activity against both yeast strains of Candida tropicalis Y26 and Saccharomyces cerevisiae Y39. On the other hand, ethyl acetate extracts of all cyanobacterial species showed antifungal activity against Saccharomyces cerevisiae YH.