Objective To analyze the current situation and influential factors of late diagnosis of newly identified HIV/AIDS cases from medical institutions in Anhui Province from 2018 to 2022. Methods The database information of the newly identified HIV/AIDS cases from medical institutions in Anhui Province from 2018 to 2022 was obtained from the National AIDS Comprehensive Information System of China information system for disease control and prevention.6 747 cases were divided into two groups:late diagnosis and non-late diagnosis.The logistic regression analysis was used to analyze the influential factors of late diagnosis. Results A total of 6 747 newly identified HIV/AIDS cases from medical institutions were analyzed,and the mean age was (47.67±16.87) years.The proportion of late diagnosis was 43.38%(2 927/6 747);Moreover,the proportions of late diagnosis from 2018 to 2022 were 44.61%(571/1 280),45.70%(638/1 396),44.93%(580/1 291),41.80%(612/1 464)and 39.97%(526/1 316),respectively.Compared with the age 0 to 19 group,the groups of age 20 to 39,age 40 to 59,and age≥60 had a higher risk of late diagnosis (OR=3.212,95%CI:2.098-4.920;OR=3.946,95%CI:2.536-6.137;OR=3.589,95%CI:2.281-5.649).Compared with STD clinic,other patients testing services and preoperative examination group had a higher risk of late diagnosis (OR=2.042,95%CI:1.670-2.496;OR=1.483,95%CI:1.197-1.838).The male cases had a higher risk of late diagnosis (OR=1.446,95%CI:1.245-1.680) than that of the female cases.Compared with the high education group,the primary school or below education group,junior high school group,and senior high school group had a higher risk of late diagnosis (OR=1.353,95%CI:1.109-1.651;OR=1.378,95%CI:1.150-1.651;OR=1.277,95%CI:1.047-1.559). Conclusion The proportion of late diagnosis among newly identified HIV/AIDS cases in medical institutions in Anhui Province showed a decreasing trend,but the overall proportion is still relatively high.The main reason for late diagnosis are related to the middle-aged and elderly individuals,other testing services,male patients,and patients with lower education level.Thus,medical institutions need to provide HIV testing and consultation,expand the testing scope of key departments and inpatients,strengthen the professional training of medical personnel in medical institutions,and improve the pertinence and effectiveness of publicity knowledge.