Background Mycobacterium bovis BCG osteitis is a rare complication of BCG vaccination. Despite some case reports of BCG osteitis in Korea, clinical presentations and incidence of BCG osteitis are not well investigated. This study aimed to evaluate the clinical characteristics of BCG osteitis from a single center experience during a recent 10 year period. Methods The study subjects included children diagnosed with BCG osteitis in the Seoul National University Hospital from January 2007 to June 2017. M. bovis BCG was confirmed by multiplex PCR which differentiates M. bovis BCG from other M. tuberculosis complex strains. Results Eighteen cases of BCG osteitis were included. BCG coverage of 2007-2016 was estimated ＞95% and ratio of inoculation route was 31% by intradermal and 69% by multiple puncture. The median age was 16.5 months (range, 7-33) and 11 (61.1%) were male. Sixteen (88.9%) received BCG Tokyo strain in multiple puncture method and two others (11.1%) received intradermal Danish and Tokyo strain, respectively. The median age at BCG inoculation was 23 days (range, 2-36). Common symptoms were pain (76.5%), swelling (76.5%), and refusal to use the affected limb (41.2%). Fever (≥38.0℃) was accompanied in 29.4%. Patients presented to the hospital from 2 to 110 days after the onset of symptoms. Except two cases with multiple bone involvement, the femur (43.8%), tarsal bone (25%), and tibia (12.5%) were common sites. The initial bone x-ray showed demarcated osteolytic lesions (58.5%) and cortical breakages (35.3%). Of the eight affected long bones, abscess lesions were located at the epiphyses on MRI. All underwent surgical drainage. Antituberculosis regimens consisting of isoniazid and rifampicin were continued for median duration of 12 months (range, 12-31). During the follow-up of median of 3.6 years, 33.3% required repeated surgical drainage due to persistent pain and swelling. Most (88.2%) recovered without evident sequelae, but two had evident length discrepancy or angular deformity of the affected lesions. Conclusions This study found 18 cases of BCG osteitis from a single center during a 10-year period. Clinical characteristics illustrated in this study can be helpful in diagnosing BCG osteitis. Further research is needed to evaluate the relation between dose and strain of BCG and the development of serious adverse reactions.