A 72-year-old male developed shock syndrome after a single dose of bromocriptine. He had undergone uncomplicated subtotal removal of an invasive prolactinoma in our department. The patient had normal ranges of pituitary hormones apart from hyperprolactinemia (167.7 ng/ml) after surgery. An acute suppression test with bromocriptine (2.5 mg per os) was done in the supine position 6 days following surgery. Three and a half hours after bromocriptine administration, he suddenly complained of anterior chest discomfort in bed. Cyanosis and profuse diaphoresis were noted. His blood pressure was 80/60 mmHg. Electrocardiography revealed sporadic premature contractions and slight depression in the ST segments. He recovered in about 10 hours after a rapid infusion of corticosteroid and lactic Ringer solution, and was discharged without sequelae. This is a very rare complication of bromocriptine, but the cardiovascular function of patients taking bromocriptine for therapeutic and diagnostic purpose should be monitored carefully.