Ziziphus mauritiana Lam. is a widespread shrub or tree of the Sahel region, where it grows wild and is used for various purposes, including nutrition, medicine, and firewood. Current domestication programs focus on using the local species as rootstock for the improved imported Asian cultivars to provide tolerance to pests and diseases. The plant plays an increasing economic role in the livelihoods of local Sahelian populations, but despite this there is little genetic information about it. The purpose of our study was to determine the genome size estimate and chromosome numbers of Z. mauritiana germplasm collected from eastern Senegal, West Africa. Genome size estimates were determined using flow cytometry, and chromosome count was achieved using chromosome spreads of actively growing root tips. The mean, median, minimum, and maximum genome size estimates (1Cx-DNA) of Z. mauritiana were 418.74 Mb, 417.45 Mb, 410.72 Mb, and 432.12 Mb, respectively. Plants of the germplasm investigated were found to be octoploid with a chromosome number of 2n = 8x = 96. The genetic information gathered in this study can be useful for phylogenetic studies, sequencing projects, and domestication programs that focus on controlled pollination for the development of improved Z. Mauritania cultivars in the Sahel region.