Objective To analyze the basic characteristics of 1885 inpatients with rare diseases in a 3A hospital from January 1 to December 31,2023,so as to provide reference for the management of diagnosis and treatment of rare diseases and the formulation of policies.Methods Based on the medical record homepage data of rare disease inpatients in a tertiary hospital in 2023,analyze the basic characteristics and hospitalization cost structure of rare disease inpatients.Results The hospital ad-mitted 1 885 inpatients with rare diseases in 2023,accounting for 0.81%of the total number of discharged patients,with a male-to-female ratio close to 1:1.Patients aged over 60 accounted for 45.57%,followed by patients aged 45-59(26.47%),patients aged 19-44(20.9%)ranked third,and patients under 18 accounted for less.Rare diseases cover 11 disease classification sys-tems and including 80 diseases,which accounts for 38.65%of the rare diseases in the catalogue.The top ten diseases accounted for 70.56%of the total number of patients,and the top three diseases were progressive fibrosing interstitial lung disease,idio-pathic pulmonary fibrosis and primary biliary cholangitis.Patients under 1 year old accounted for 0.08%,patients aged 2-18 years accounted for 5.19%,patients aged 19-44 years accounted for 19.55%,patients aged 45-59 years accounted for 26.62%,and patients over 60 years old accounted for 48.57%.There was a large difference in the male-female ratio in four diseases:idio-pathic pulmonary fibrosis,amyotrophic lateral sclerosis,Takayasu's arteritis,and primary biliary cholangitis.From the perspec-tive of cost structure,the top ten rare diseases account for a high proportion of diagnosis fees,medicine fees and consumables fees.Conclusion Patients account for a high proportion of rare disease inpatients in the hospital and have a wide coverage of disease types.The overall male-female ratio of patients with rare diseases is similar,but the characteristics of the diseases are dif-ferent.The characteristics of rare diseases determine the structural characteristics of hospitalization expenses.Hospitals should improve the discipline construction and provide more resources for the diagnosis and treatment of rare diseases.To make guide-lines for the diagnosis and treatment of rare diseases and strengthen the training of doctors,so as to realize the early diagnosis and treatment of rare diseases.The state should continue to promote access to medication for rare diseases.