Selenium sulfide is a well-known bioactive chemical whose biosynthesis as a nanoparticle (NP) is a controversial issue. In the present study, we employed Saccharomyces cerevisiae to generate a novel synthetic process of selenium sulfide NPs. The addition of selenium/sulfur precursors to S. cerevisiae culture produced NPs, which we isolated and characterized the physicochemical properties, toxicity, and antifungal activity. Transmission electron microscopy indicated the presence of the NPs inside the cells. Selenium sulfide NPs were successfully synthesized with average size of 6.0 and 153 nm with scanning electron micrographs and 360 and 289 nm in Zeta sizer using different precursors. The presence of sulfur/selenium in the particles was confirmed by energy-dispersive X-ray spectroscopy and elemental mapping. Fourier-transform infrared spectroscopy supported the production of selenium sulfide NPs. X-ray diffractograms showed the presence of characteristic peaks of selenium sulfide NPs which were further confirmed by mass spectrometry. The obtained NPs strongly inhibited the growth of pathogenic fungi that belonged to the genera Aspergillus, Candida, Alternaria and the dermatophytes, while no cytotoxicity was observed in MTT assay. In conclusion, efficient green synthesis of selenium sulfide NPs with appropriate physicochemical properties is possible in bio-systems like S. cerevisiae. (C) 2019 Elsevier Inc. All rights reserved.