INTRODUCTION: The coexistence of autoimmune diseases is well recognized. Approximately 25% of patients with autoimmune disease tend to develop additional autoimmune diseases. Similarly, autoimmune hepatitis (AIH) has been seen with many different autoimmune diseases. Some of the common associations include autoimmune thyroiditis, vitiligo, rheumatoid arthritis, celiac disease, systemic lupus erythematodes, type 1 diabetes, multiple sclerosis, polymyalgia rheumatica, and urticaria. However, the coexistence of AIH and pernicious anemia (PA) is extremely rare. To the best of our knowledge, there is only one documented case of AIH associated with PA. CASE DESCRIPTION/METHODS: A 70-year-old woman of Iranian origin presented to the gastroenterology clinic complaining of poor appetite and an 8 lb weight loss over the last two months. Past medical history was notable for Type 1 autoimmune hepatitis and hypothyroidism (Table 2). She denied changes in bowel habits, hematochezia, melena, hematemesis, heartburn, dysphagia, or odynophagia. Family history was negative for gastrointestinal cancer. Laboratory studies were significant for microcytic anemia, B12, and iron deficiency. Esophagogastroduodenoscopy (EGD) showed diffuse gastric mucosal atrophy, and the pathology from the body of the stomach was consistent with chronic gastritis. Additional testing was positive for parietal cell antibody (PCA) and intrinsic factor blocking antibody (AIF), confirming the diagnosis of PA. She was subsequently advised to initiate oral iron and vitamin B12 supplementation, which led to normalization of hemoglobin. DISCUSSION: Several different autoimmune diseases have been associated in patients with AIH. Approximately 20% - 30% of type 2 AIH patients have additional autoimmune diseases. Initially, we speculated the association between AIH and PA was common. However, the literature suggested otherwise. After literature review, only one documented case of AIH co-occurring with PA was found (Table 1). As evident by our patient's history, it is essential to consider PA as a differential for patients presenting with AIH and anemia. It is also vital to consider screening these patients for other autoimmune disorders, given the increased prevalence of co-occurring autoimmune diseases.Image 1.: Chronic Gastritis with Intestinal Metaplasia of the Glands.Table 2Table 1