In Sub-Saharan Africa peanut fields, where soils are poor in nutrients and fertilizers are not easily available to farmers, improving atmospheric nitrogen fixation in peanut which can fix more than half of its nitrogen needs from atmospheric nitrogen, is an important lever for reaching higher yields. However, our knowledge on the genetic base of biological nitrogen fixation (BNF) in cultivated peanut still needs to be improved. This study aims at exploring cultivated peanut diversity to better understand the genetic base of BNF variation in this crop. A core-collection of 300 peanut accessions of African origin were evaluated during the rainy season 2022, from July to October at ISRA-Nioro experimental station for chlorophyll content, nodules number, plant dry weight, yield, shoot dry abundance in 15N and fixed nitrogen. No inoculation and fertilization were applied. SNP genotyping data from these accessions will then be used to perform genotype-phenotype association studies to identify genomic regions involved in BNF. First data analyses showed variability within the population and significant differences were observed between genotypes for all evaluated traits. Later, this study will provide knowledge on the peanut genomic regions involved in BNF. It will also allow us to select contrasting accessions for BNF to investigate if the observed differences are due to the recruitment of different rhizospheric microbiomes. Accessions showing high levels of BNF could then be used as donor parents in peanut breeding programs to improve BNF of elite cultivars.