Carpal osteoid osteomas are extremely rare, and only six cases in the pisiform have ever been described, but all concerned exclusively adults. We have treated a unique case of osteoid osteoma in the pisiform of a 13-year-old girl. We excised en bloc the nidus, which resulted in total excision of the pisiform. At follow-up after 15 years there was no recurrence and the patient remains asymptomatic with equal functionality of both hands. Henceforth, we must include osteoid osteoma in the differential diagnosis of pisiform lesions in children. En bloc resection prevents its recurrence and even the complete pisiform excision renders excellent results.