Two cases of "yellow-nail syndrome" are reported: in the first, nail changes began eight months after the diagnosis of a breast cancer; in the second, yellow dystrophic nails were associated with hypertrophic osteoarthropathy due to pleuro-pulmonary metastatic lesions. Clinical features are described: characteristic nail changes, lymphoedema, pleural effusions, and, often bronchopulmonary infections and sinusitis. Various combinations are seen, and the time between the development of the different manifestations may vary from several months to many years. Among associated diseases, immunological changes and malignancy are emphasized. The pathogenesis remains obscure. Accurate part taken by lymphoedema, immunological changes, is unknown, and the relationships between "yellow-nail syndrome" and malignancy are still uncertain.