In three patients gynaecomastia was diagnosed: a 22-year-old man with concomitant thyrotoxicosis due to an extensively metastasized extragonadal choriocarcinoma, a 53-year-old man with hypogonadism due to Klinefelter's syndrome that was biochemically obscured due to medications leading to elevated prolactin levels, and a 62-year-old man with acromegaly and secondary hypogonadism due to a mixed prolactin and growth hormone secreting pituitary adenoma. Gynaecomastia calls for thorough evaluation.