• Patrick Ije Ode
  Department of Biological Sciences, Faculty of Science, Rev. Fr. Moses Orshio Adasu University Makurdi, Nigeria.
  




• Ibrahim Mohammed
  Genomic and Molecular Laboratory, Kano Independent Research Centre Trust, Kano State, Nigeria.
  




• Elizabeth Odije Ogbogo
  Department of Biological Sciences, Faculty of Science, Rev. Fr. Moses Orshio Adasu University Makurdi, Nigeria.
  




• Cephas Iye Owina
  Department of Biological Sciences, Faculty of Science, Rev. Fr. Moses Orshio Adasu University Makurdi, Nigeria.
  




• Daniel Ikpe Acha
  Department of Biochemistry, Bayero University, Kano, Nigeria.
  

Groundnut (Arachis hypogaea) is a vital nutrient-dense legume widely consumed in Nigeria, yet highly susceptible to post-harvest mycotic deterioration. This study investigated the fungal contamination of stored groundnut seeds in Makurdi, and evaluated its impact on the seed proximate composition. Groundnut samples were collected from Wurukum Market, Makurdi. Fungal contaminants were isolated using the standard Blotter Method, and identified based on morphological characteristics. Healthy seeds were artificially inoculated with pure isolates, and proximate parameters were determined using standard methods of Association of Official Analytical chemist (AOAC), and compared via ANOVA (p < 0.05). Four fungal species were identified: Alternaria sp. (45.00%), Aspergillus niger (30.00%), Aspergillus flavus (15.00%), and Phytophthora species. (10.00%). Fungal infection was observed to cause significant nutritional degradation across all isolates (p < 0.05). Compared to healthy control seeds, infected seeds exhibited significant reductions in crude fat (from 7.27% to 1.80–4.02%), crude protein (from 21.60% to 7.24–9.82%), crude fibre (from 1.13% to 0.46– 0.60%), and ash content. Conversely, moisture content (8.36–10.07% vs. 3.64%) and carbohydrate content (75.83–77.42% vs. 62.64%) increased significantly in infected seeds. The Principal Component Analysis (PCA) showed that PC1 (84.58%) and PC2 (11.75%) together accounted for 96.34% of the total variance. This study showed that, mycotic contamination severely impairs the nutritional and commercial value of stored groundnuts by depleting essential lipids and proteins. To preserve nutritional quality and safeguard consumer health, improved post-harvest handling, adequate drying, and hygienic storage practices are strongly recommended.