OBJECTIVES: Adverse drug reactions (ADR) appear more frequently then what is actually reported and registered. The aim was to establish intensive monitoring system and to analyze ADR in hospitalized patients. METHODS: Prospective study covered 200 patients hospitalized in Cardiology Center, Clinical Center of Montenegro. ADR were collected in the following way: patients were interviewed on the basis of the symptoms list and any signs which could point to eventual ADR.  Secondly, lab tests and other available parameters were observed. RESULTS: At the time when interviews took place, patients received on average 7.96±2.63 medicines (2-17). In total, 67 patients (34%) had 75 ADR. Twenty-one ADR (28%) are classified as serious. Fifty-four ADR have resulted in the recovery of the patient (72%), eight had as an outcome prolonged hospitalization (11%), another 8 were life threatening (11%), while 5 ADR (6%) were the cause of the hospitalization. The most frequent ADR which had as an outcome admission to hospital were caused by digoxin (40%), prolonged hospital stay by furosemide (38%), while the most frequent registered ADR which were life threatening were caused by streptokinase (50%). CONCLUSIONS: Monitoring ADR in patients using cardiovascular drugs is a matter of importance since this class of medicine is usually used by elderly patients with critical conditions and underlying diseases.