The discovery of an anterior asymptomatic mediastinal mass with acromegaly creates a dilemma for the clinician. As acromegaly can be due to a pituitary tumor but also to an ectopic production of GHRH, the first diagnostic step consists of finding the etiology of the disease in order to use adequate treatment. This can be complicated by the fact that acromegaly can be associated with other tumors (for instance in MEN-1 disease and Carney Complex) and because chronic GH hypersecretion can stimulate tumor overgrowth and perhaps tumor formation. We describe the case of a 44-year-old acromegalic woman with an anterior mediastinal mass. We present the different diagnoses and a review of the literature.