We report on a woman with clinical Cushing's syndrome confirmed by biochemical data. The Cushing's syndrome was shown to be ACTH dependent and inferior petrosal sinus sampling pointed to an ectopic source. After resection of a lung carcinoid a well documented remission of Cushing's syndrome was obtained. At recurrence of Cushing's syndrome 18 months later the ACTH source could not be located despite extensive diagnostic procedures. Clinical and biochemical control of hypercortisolism was achieved by continuous subcutaneous infusion of octreotide. During a brief interruption of treatment recurrence of clinical and biochemical signs and symptoms of Cushing's syndrome were demonstrated. We conclude that in this case of occult ectopic ACTH secretion, presumably due to recurrent lung carcinoid, continuous subcutaneous infusion therapy with octreotide resulted in clinical and metabolic control of Cushing's syndrome for 8 years. In addition excellent tumour growth control was achieved as repeated searches for tumour recurrence or metastasis remained negative.