One the basis of two special typical cases, the authors detail the symptoms and signs and consider the physiopathology of inappropriate secretion of antidiuretic hormone related to vincristine. Urinary ADH was measured in both cases. ADH levels could be studied on ten consecutive occasions during the course of one of the cases (obs. n 1). Eleven similar cases have been found in the literature. ADH was measured in only three of them. Methods of treatment are considered, with particular emphasis on the role of demeclocycline.