10.22376/ijpbs.2019.10.1.p1-12 Volume 11 Issue 2 2020 (April-June) The present study illustrates the biosynthesis of colloidal silver nanoparticles (AgNPs) from marine seaweed lessThan b greaterThan lessThan /b greaterThan lessThan i greaterThan Colpomenia sinuosa lessThan /i greaterThan and their antifungal efficacy was determined against dermatophytic and non-dermatophytic fungi. The dermatophytic fungi used in this study are lessThan i greaterThan Microsporum nanum lessThan /i greaterThan (ATCC 28951) lessThan b greaterThan lessThan /b greaterThan and lessThan i greaterThan Trichophyton mentagrophytes lessThan /i greaterThan (ATCC 28185 lessThan b greaterThan ) lessThan /b greaterThan whereas the non dermatophytic fungi lessThan i greaterThan Aspergillus flavus lessThan /i greaterThan (ATCC 20048) and lessThan i greaterThan Rhizopus microsporus lessThan /i greaterThan (ATCC 22960). The rich content of phytochemicals, bioactive compounds and secondary metabolites in marine seaweed lessThan i greaterThan Colpomenia sinuosa lessThan /i greaterThan possess the reducing/capping agents that may be environmentally acceptable and eco-friendly for the biosynthesis of silver nanoparticles. The efficacy of biosynthesized silver nanoparticles from marine macroscopic brown alga was performed using Kirby Bauer Method and the silver nanoparticles biosynthesized was characterized by UV-vis spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) and Thermo gravimetric analysis. Particle size distribution and morphology were investigated by scanning electron microscope which showed silver nanoparticles in the size range of 54-85 nm. The average size of the silver nanoparticle indicated by TEM analysis was found to be 34 nm. The antifungal efficacy of silver nanoparticles at the concentration 30 µg/mL revealed greater efficacy in dermatophytic fungi while lessThan i greaterThan Rhizopus microsporus lessThan /i greaterThan as non dermatophytic fungus showed better antifungal activity when compared to the standard fungal antibiotics used. Dr Vishnu Kiran Manam and Dr Murugesan Subbaiah AgNps, biosynthesis, Colpomenia sinuosa, antifungal efficacy, dermatophytes, non dermatophytes 59-68