Giant congenital melanocytic nevus (CMN) is an uncommon nevus in newborns which defined as a predisposing factor for malignancies such as melanoma. Other malignancies such as rhabdomyosarcoma rarely have seen in a giant CMN. We have some reports about rhabdomyosarcoma arising from CMN. Rhabdomyosarcoma presents with nodules, pedunculated lesion, ulcers and skin tags in these patients. Except an adult case, other cases are children. Our case is second patient with alveolar type which have poorest prognosis. According to these reports serially examination, parental education and serious investigation for any changes in integrity of CMN is recommended.