A16 years old male presented with pain in right hip and swelling in right thigh since one year. The radiograph of pelvis with both hips revealed elongation of neck of right femur with overlying soft tissue swelling shadow. MRI brain revealed hyper intense foci on T2W images in left parietal lobe. After evaluation the Radiological diagnosis of Neurofibroma of right thigh with elongation of neck of right femur, with hamartoma in left parietal lobe was kept. On basis of clinical and radiological features the final diagnosis of Neurofibromatosis I (NF I) was made. Neurofibromatosis type I is a neuro cutaneous syndrome which present as multi system manifestations. Focal lengthening of bone is an unusual manifestation of neurofibromatosis type I, so whenever there is focal lengthening of bone associated with an overlying mass lesion one should suspect NF I and should look for its cutaneous manifestations.