OBJECTIVE: This study is aimed to investigate clinical time course in the diagnosis of SLE,clinical features at disease onset,and their effects on organ damage and disease activity METHODS: We evaluated 244 patients in the Korean Hanyang Lupus Cohort by medical record review and direct interview:the time at disease onset,clinical diagnosis,and diagnosis meeting ACR criteria for SLE (ACR diagnosis),clinical features at onset,SLICC/ACR damage index,SLAM-R,education,and income. The risk factors of delayed diagnosis and their effect on damage and activity were examined with uni and multivariate analyses. RESULTS: Mean age and disease duration were 33.9 (+/- 11.9)and 6.2 (+/- 4 .4 )years. The mean time from onset to clinical diagnosis and ACR diagnosis were 2.4 (+/- 3.6)and 2.7 (+/- 3.3)years.The clinical features at disease onset were as follows;arthritis (46.3%),skin rash (13.7%),fever (7.4%),hematologic disorder (7.4%),nephritis (5.7%),Raynaud phenomenon (3.7%),neuropsychiatric syndrome (2.4%).Diagnosis was delayed when oral ulcer,photosensitivity,and arthritis were presented as 1st clinical features compared to when nephritis, malar rash,and fever as 1st clinical features.Delayed diagnosis (based on median time in clinical diagnosis)was not associated with damage,disease activity,education,and income. CONCLUSIONS: SLE was diagnosed late over 2 years after first symptoms onset and the time interval from clinical symptoms to ACR diagnosis is about 4 months;the delayed diagnosis and the prognosis in terms of damage and activity might depend on 1st clinical features.