This study aimed to assess the effect of extracts of Lyngbya strain, MZUCC066, prepared in different solvents (methanol-100%, ethanol:water-3:7 and dichloromethane:isopropanol-1:1) against six microorganisms that comprise three chlorophycean algae (Chlorella vulgaris, Scenedesmus quadricauda and Selenastrum capricornatum), one cyanobacterian alga (Anabaena variabilis), and two bacterial strains (Bacillus subtilis, ATCC11774 and Bacillus pumilus, ATCC14884). Among the algal test organisms, the highest inhibition was found in S. quadricauda (70%) by dichloromethane:isopropanol extract of Lyngbya followed by A. variabilis (41%) by the same extract. When tested on bacterial test organisms, the highest inhibition zone diameter of 15.67 mm was found in B. subtilis by dichloromethane:isopropanol extract and followed by 14 mm in B. pumilus by the same extract at 100 µl concentration. Minimum inhibitory concentrations of each extract on all the organisms were varied. The present study suggests that Lyngbya has specific bioactivities against different groups of microorganisms.