ABSTRACT
A patient with a slow-growing fibrosarcoma of ovarian origin developed attacks of hypoglycaemia. Estimations of plasma insulin-like activity and immunoassay of plasma insulin under a variety of conditions showed no evidence of abnormal insulin secretion. In addition, the responses to glucagon, tolbutamide, and L-leucine showed no definite abnormality. Possible mechanisms for the occurrence of the hypoglycaemia are discussed.