The Rothmund-Thomson syndrome (RTS), also called poikiloderma congenitale is a rare autosomal recessive disease first described in 1868. This syndrome includes most frequently seen skin lesions (atrophy, telangiectases, pigmentation), cataracts and bone defects (dysostosis, dysplasia). Some authors describe an association with malignancy. We report three cases of Rothmund-Thomson syndrome associated with osteosarcoma. After cutaneous epithelioma, osteosarcoma is the most frequent malignancy. Thus, patients with RTS need a careful survey. The treatment did not differ from sporadic osteosarcoma. Chemosensitivity and toxicity are also not different.