Werner syndrome (WRN), or adult progeria, is a very rare, autosomal recessive disorder characterized by the appearance of accelerated aging, including cataracts, gray hair, skin atrophy, and atherosclerosis. This syndrome is caused by mutations in the WRN gene and had a high risk of a spectrum of rare neoplasms including: i) non-epithelial malignant or pre-malignant tumors/conditions, osteosarcomas and soft tissue sarcomas, malignant melanomas, myeloid leukemia and myelodysplastic syndrome; ii) an epithelial neoplasm, thyroid carcinoma, and iii) meningiomas. Recently, authors experienced a case of Werner syndrome complicated by bone metastasis of rhabdomyosarcoma in a 20-year old Korean man. The patient revealed a painful mass on his right knee and progeroid features, short stature, scalp alopecia, abnormal dentition, craniofacial disproportion, hypothyroidsm, cataracts and osteoporosis. The onset of symptoms of Werner syndrome generally precedes any later symptoms of associated conditions, such as malignant tumor. Therefore, early recognition of Werner syndrome is important to assist identification of malignant tumors at an early stage in this patient group.