Epidemiological study of Langerhans cell histiocytosis (LCH) has been limited due to its rarity and multisystemic involvement. The aim of this study was to investigate the epidemiological features of LCH via the clinical data warehouse (CDW). Clinical data of 30 LCH patients from the all departments of a tertiary referral hospital between 2003 and 2012 were analyzed retrospectively by searching the CDW. The male-to-female ratio was 2.8:1. The age of onset ranged 7 days to 57 years with a median of 13 years. Of the patients, 36.7% presented initial symptoms before the age of 10 years. The involved organs at diagnosis were: bone (66.7%), skin (16.7%), lungs (13.3%) and lymph node (3.3%). For all of the 30 cases, there were 31 disease sites because of a single case of multisystemic disease involving both skin and bone. Of the 96.7% of patients with single-system disease, 69.0% had bony involvement. This study elucidated the clinical features of LCH from all the departments of a tertiary hospital via the CDW, which suggests a potential role of the CDW as a new epidemiological approach for rare diseases.