The recognition of extrapituitary ACTH-secreting tumors is of great importance, not only theoretically but also in practice, in that it permits rational and radical therapy of the relative Cushing's syndrome and avoids more traumatic and risky surgery such as the destruction of the hypophysis and total adrenalectomy. In some cases, however, a systematic search for these tumors, which can be extremely small, is unsuccessful even when the most modern diagnostic tools are employed. Thus, it is still sometimes necessary to resort to total adrenalectomy for provisional control of the Cushing's syndrome, delaying definitive treatment until the tumor makes itself evident. Two clinical cases are described in which, although elements suggesting the possibility of an ectopic neoplasia were present at the time of adrenalectomy, they were not recognized as such, and the tumor responsible for the syndrome was not identified until many years later.