Park JY, et al. - The prevalence of heterotopic ossification (HO) formation following the ulnar collateral ligament (UCL) reconstruction was assessed by the experts. They also evaluated the clinical outcomes after the HO treatment. Following UCL reconstruction, the prevalence of HO formation was approximately 5% and it was noted to be raised with transient ulnar neuropathy. Following the UCL reconstruction, the HO formation, especially in the early stages after the operation ought to be carefully observed by the surgeon. Favourable outcomes of the HO treatment following UCL reconstruction were noted with appropriate treatment.