Screening for sources of biologically active compounds capable of treating cancer is the main target of many researches nowadays. The anticancer as well as antifungal activities of the methanolic extracts of 4 microalgae (Spirulina maxima, Chlorella salina, Nannochloropsis oceanica, and Nannochloropsis oculata) were investigated. Among the microalgal extracts studied, the extract ofSpirulina maxima exhibited promising anti-breast cancer activity causing 75.50±1.76% cytotoxicity at concentration of 200 µg/ ml, followed by N. oceanica extract  (46.86±8.15% cytotoxicity) at the same concentration. Moreover, the same extract in addition to that of Nannochloropsis oceanica exerted anti-Fusarium activity. At the same time, both extracts showed weak antifungal activities against Aspergillus niger and A. flavus, while no activity was recorded against Penicillum chrysogenum.