Objectives: The aim of this study is to synthesize silver nanoparticles using the algal extract of Padina tetrastromatica and evaluate its antifungal activity against pathogenic fungus isolated from clinical samples.Results: Formation of brown color at 15 minutes indicates the production of silver nanoparticles by the extract of brown algae P. tetrastromatica. Surface plasmon resonance band was centered at 440 nm which was observed by UV-vis spectrophotometer. SEM image revealed spherical and cubical nanoparticles with high agglomeration, and energy-dispersive X-ray illustrates elemental components of silver formed at 3 keV. TEM shows spherical, truncated, and ellipsoidal nanoparticles and also it evidences the algae compounds that are capped with nanoparticles. SAED pattern proved four diffraction face-centered cubic rings at (111), (200), (220), and (311) which indicates the crystalline nature of nanoparticles. Silver nanoparticles show high inhibition activity against Fusarium sp, Aspergillus niger, Candida albicans, Aspergillus fumigatus, and Aspergillus flavus at different concentrations. P. tetrastromatica-mediated synthesis of silver nanoparticles shows rapid and eco-friendly silver ion reduction process.Methods: Dried algal biomass was used to prepare the pure algal extract and added with 1 mM AgNO , and the color change was noted and recorded by ultraviolet (UV)-vis spectrophotometer. The morphological characteristics were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Crystalline structure was analyzed by SAED pattern. Antifungal activity was performed by agar well diffusion method against various pathogenic fungi.Conclusion: Therefore, this present study elucidates that algae-mediated synthesized silver nanoparticles have antifungal activity against pathogenic fungi, so it can be developed as a novel medicine for human welfare in biomedical applications in the near future.Keywords: Padina tetrastromatica, Silver nanoparticles, Transmission electron microscopy, Antifungal activity, Green synthesis.