Buckwheat is an annual plant in the Polygonaceae family that is classified as a pseudocereal. It is mainly used as a source of antioxidants and gluten-free foods. Buckwheat yield and quality depend on genetic properties, environmental conditions, and cultural practices. Therefore, this study aimed to determine the effects of organomineral fertiliser on buckwheat yield and antioxidant activity in the environmental conditions of Bosnia and Herzegovina. The treatments used in this research consisted of a combination of fertilisers (fertilised and nonfertilised) and two buckwheat species (common and tartary buckwheat). During 2019, two field experiments were conducted in Butmir and Kakanj (B&H). The tested properties were plant height, a mass of 1000 kernels, yield, total phenolic, and antioxidant activity of leaves, flowers, and kernels. Yield depended on the treatment, ranging from 946.9 kg ha -1 to 1438.6 kg ha -1 . The total phenol contents were affected by fertiliser treatment, buckwheat species, and plant organs. The kernel had the lowest total phenol content (30.55 mg GAE g -1 ), whereas the flowers had the highest content (158.03 mg GAE g -1 ).