Abstract In this study, the growth-inhibitory effect of polysaccharide (1,3)(1,4)-β-d-glucan from oat, Avena sativa L. grains was explored on the human skin melanoma HTB-140 cells in vitro. The oat β-d-glucan (OBG) exerted cytotoxic action on HTB-140 cells. After 24 h of incubation, LD50 (concentration at which 50% of the cells were found dead) was obtained of 194.6 ± 9.8 μg/mL. The oat β-d-glucan