CURRENTLY, there is a growing need to develop environmentally…. benign nanoparticle synthesis process that does not use toxicchemicals in the synthesis protocols. Synthesis of nanomaterials bybiological approach is innovative, cheaper and environmentallyfriendly. In this regard, the present study focused on the synthesis ofsilver nanoparticles from the microalga Isochrysis galbana. The silvernanoparticle produced by marine microalga Isochrysis galbana whenincubated with silver nitrate solution at the same culture condition for24 h and was detected by UV-Vis spectrophotometer, Energydispersive X-ray (EDX-ray) and Transmission electron microscope.The synthesized silver nitrate nanoparticles from the marine microalgaIsochrysis galbana showed the pronounced antibacterial activityagainst the tested human pathogens Escherichia coli and Proteusvulgaris. The above eco-friendly synthesis procedure of silver nitratenanoparticles could be easily scaled up in future for the industrial andtherapeutic needs.