Background: Sjögren's syndrome is a chronic autoimmune inflammatory disease characterized by lymphocytic infiltration of exocrine glands, typically presenting with symptoms such as xerostomia (dry mouth) and xerophthalmia (dry eyes). This disease can appear as an isolated condition or in association with other diseases. It is most commonly associated with rheumatologic disorders such as rheumatoid arthritis and systemic lupus erythematosus, but in rare cases, it may also be associated with other autoimmune diseases involving various organ systems. Autoimmune hepatitis is a chronic liver inflammation characterized by elevated serum globulin and antibody levels. The coexistence of Sjögren's syndrome and autoimmune hepatitis is very rare, with some sources indicating an incidence of only 1.7%. In our clinical case report, a rare occurrence was observed in a 52-year-old female who had been diagnosed with Sjögren's syndrome in 2022 and later developed symptoms of hepatitis, leading to a diagnosis of autoimmune hepatitis. When autoimmune hepatitis coexists with other autoimmune diseases, it often presents with mild clinical symptoms, which may delay the diagnosis. Case report: A 52-year-old female patient presented in 2020 with complaints of dry eyes and mouth, blurred vision, decreased saliva production, fatigue, and occasional swelling of the lymph nodes, as reported during her medical history. In December 2022, she was seen by a rheumatologist at the Mongolia-Japan Medical Center. Laboratory tests revealed positive results for anti-SSA52, CENP-B, ANA IgG, and RF, with altered liver function (see Table 1). A Shirmer test was positive, and saliva production was ≤ 0.1 mL/min. According to the ACR-EULAR 2016 diagnostic criteria, she scored 5 points, confirming the diagnosis of Sjögren's syndrome. Treatment was initiated with hydroxychloroquine and corticosteroids, along with medications for gastric protection, liver protection, and prevention of complications. In March 2023, during a follow-up visit, laboratory tests showed altered liver function (see Table 1). Hepatitis B and C antibodies were negative, and Liver-9-line results were normal. Due to the positive clinical dynamics of Sjögren's syndrome, the dose of hydroxychloroquine was reduced, and other treatments were continued. The patient was also advised to see a gastroenterologist for further evaluation. In August 2024, she presented to the gastroenterology department at Intermed Hospital with complaints of left abdominal pain and jaundice. Upon examination, abdominal ultrasound was normal, but laboratory results showed elevated IgG (132 H), ANA (>400 U/L), ALT (119.2 U/L), and AST (132.8 U/L), which raised suspicion of autoimmune hepatitis. Consequently, a liver biopsy was performed. Liver Biopsy (August 2024): The liver tissue shows a portal triad with 13 portal trios, where there is mild infiltration of lymphocytes, eosinophils, and a few neutrophils around the portal triads. Focal macrosteatosis of hepatocytes and bile stasis are observed. In Masson’s trichrome stain: There is fibrosis around the portal triads with connective tissue proliferation (ISHAK-1). In PAS staining: Focal positive staining is observed within the hepatocytes. According to the international autoimmune hepatitis diagnostic criteria, the diagnosis of autoimmune hepatitis was confirmed with a score of 8 (ANA +2, IgG +2, Biopsy +2, HBV HCV negative +2). Liver biopsy confirmed the diagnosis of primary sclerosing cholangitis. Treatment with corticosteroids and choleretic therapy was initiated, and a follow-up visit is planned in one month. In September 2024, upon follow-up, liver function had improved compared to previous tests, and treatment was continued. The patient is now under ongoing monitoring by both a gastroenterologist and a rheumatologist. Conclusion The coexistence of Sjögren's syndrome and autoimmune hepatitis is a rare clinical occurrence, with foreign studies reporting an incidence of less than 1%. However, if autoimmune hepatitis goes undiagnosed, it can lead to complications such as liver cirrhosis and hepatocellular carcinoma. Therefore, it is of critical importance to perform antibody tests and tissue biopsy for early detection and differential diagnosis in patients diagnosed with Sjögren's syndrome who present with liver and biliary symptoms or laboratory findings indicating liver dysfunction. This clinical case emphasizes the need for careful monitoring and early intervention.