<p>Biermer’s disease, or pernicious anemia, is an autoimmune condition marked by vitamin B12 deficiency due to intrinsic factor antibodies targeting gastric parietal cells. The relationship between Biermer’s disease and increased thrombotic risk, while uncommon, represents a critical clinical concern necessitating heightened diagnostic awareness for patients presenting with unexplained thrombotic symptoms. This report details the case of a 57-year-old Mediterranean male, with a prior diagnosis of Graves’ disease, who developed splanchnic venous thrombosis. An extensive etiological investigation revealed mild hyperhomocysteinemia, associated with an undiagnosed Biermer’s disease. Our case underscores a critical association between Biermer’s disease, hyperhomocysteinemia, and venous thrombosis, emphasizing the imperative for further research elucidating their interconnected pathogenesis.</p>