Osteoid osteoma is a benign primary bone tumor that occurs most commonly in children, adolescents, and young adults between the ages of 5 and 30 years. It is quite uncommon in patients before age 5 years (3-8% of all osteoid osteoma cases). A case of osteoid osteoma in a 13-month-old infant, who presented with increased crying at night due to pain and swelling in his right crus, is reported in this study. While it is easier to misdiagnose clinically for the younger age and imaging features are also more likely to be unspecific for differentiating from the malignancy, biopsy was performed with Jamshidi. Because of nidus formation showing osteoid osteoma in the histological examination, further surgical procedure was not necessary. At follow-up 7 months later, MRI showed sclerosis and edema around the lesion. The patient still had had pain. This made us think that excision of the tumor with jamshidi resulted in inadequate treatment due to incomplete removal of the nidus.