Objective: To understand the medical treatment and clinical characteristics of patients with IgG4-related disease (IgG4-RD) with complex clinical manifestations and easy to be misdiagnosed and missed, and to improve the recognition of this disease among doctors from relevant medical departments. Methods: A retrospective analysis was conducted on the medical records of patients diagnosed with IgG4-RD who were hospitalized and discharged from Peking University Third Hospital from January 1, 2012 to December 31, 2022. The patient' s medical visit status, clinical manifestations, laboratory examinations, diagnosis, and treatment information were summarized. Results: A total of 116 patients diagnosed with IgG4-RD were included in this study, with a male to female ratio of 2. 52∶ 1 and an average age of (61.83±10.80) years. The departments for initial visits were gastroenterology, general surgery, and ophthalmology. While the departments responsible for definitive diagnosis were gastroenterology, rheumatology and immunology, and respiratory medicine. Twenty-one patients (18. 10%) required consultation and treatment from three or more departments before receiving a definitive diagnosis. The median time from symptom onset to the initial clinic visit was 2 (1, 7) months, and the median time from symptom onset to diagnosis was 1 (1, 12) month. Twenty-four patients (20.69%) underwent surgical resection of the affected sites before diagnosis. According to the classification criteria of IgG4-RD, sixty-eight (58.62%) cases were diagnosed definitively, eight (6.9%) cases were likely to be diagnosed, and 40 (34.48%) cases were suspected to be diagnosed. In the 68 definitively diagnosed patients, the most commonly affected organs were submandibular gland, the pancreas, biliary tract, parotid in sequence. The median serum IgG4 (IgG4, immunoglobulin G4) level was 6.16 (3. 61, 12. 30) g/L. Fifty-seven patients (83.82%) were treated with glucocorticoids, and 14 patients (20.59%) were treated with immunosuppressants. The use of immunosuppressants was mainly in the rheumatology and immunology department (78. 57%). Conclusion: IgG4-RD is more common in elderly males, with submandibular gland, the pancreas, biliary tract, and parotid being most commonly affected. The distribution of initial visit departments in patients is wide. The proportion of definitive diagnosis based on pathology is relatively low. In terms of treatment, the main approach is steroid treatment, while the use of immunosuppres-sants is not widespread.