Menadione (2-Methyl-1, 4-naphthoquinone) also known as vitamin K3, is the synthetic form of vitamins K. Although it has a weak biological activity, menadione can be converted into a more intense active form in the presence of gut bacteria. It is widely used in medicine as an anti-hemorrhagic agent and also as nutritional supplement in feedingstuffs for animals. \nThe purpose of the present study is to quantify the menadione sodium bisulfite in feedingstuffs via volumetric and spectrophotometric analyses. \nThe analyses carried out on feedingstuff samples for chickens and dogs revealed concentrations of menadione sodium bisulfite of 0.5960 mg/kg and 1.424 mg/kg, respectively.\nThe difference between the results obtained using the two parallel methods did not exceed 6 %.