Non-ossifying fibroma of bone (NOF) is a common entity, more frequently found in male children and consisting of a solitary eccentric, lytic expanded lesion in the metaphysis of a long bone. The disorder is benign and most often asymptomatic but may result in a fracture requiring therapy. Of some importance is to distinguish NOF from another very similar but smaller lesion, fibrous cortical defect, which is almost always asymptomatic and eccentrically located. Even more striking is a very rarely encountered lesion known as Jaffe-Campanacci syndrome, which also occurs in children who present with typical non-ossifying fibromatous tumors but in multiple sites. In addition, these patients have some systemic and dermal findings resembling those seen in patients with Type 1 neurofibromatosis.