Abstract Funding Acknowledgements Type of funding sources: None. Introduction The medication cost of critically ill patients varies among different countries as different health care strategies are applied in each country. The data for the cost of medications in Coronary Intensive Care Units (CICUs) is sparse in the literature. Purpose The purpose of this study was to assess the cost of medications of CICU patients in a Greek tertiary care CICU and search for clinical factors associated with increased cost. Methods We conducted a prospective single-center observational study, which enrolled consecutive CICU patients of a Greek University Hospital from 1st January 2014 until 31st May 2018. The cost analysis was based on the drugs’ hospital prices, given the assumption that each drug box was used for only one patient. We included only the drug costs. Other costs (personnel costs, cost of energy, cost of specific equipment, etc.) could not be estimated on an individual patient basis, and relevant data were not also available. Results Nine hundred forty-three (943) patients were enrolled. The total medication cost was 89,234.14 EUR. The average medication cost per patient was 94.63 ± 3.60 EUR. We included 673 men (71.4%) and 270 women (28.6%). The average cost for men was 91.95 EUR, while for women was 101.3 EUR. The patients’ median age was 68 years. The average cost per age group was 82.19 EUR for patients up to 50 years, 92.89 EUR for patients 51-60 years, 98.71 EUR for patients 61-70 years, 96.2 EUR for patients 71-80 years, and 99.38 EUR for patients over 80 years. The development of sustained cardiac tachyarrhythmias (sustained ventricular tachycardia, ventricular fibrillation, atrial tachycardia, atrial fibrillation, atrial flutter) increased the medication cost by 3.41 EUR. Type of arrhythmias (supraventricular, ventricular) did not have a statistically significant impact on the cost. The mean duration of CICU hospitalization for the patients who developed tachyarrhythmias (756 patients; 80.2%) was 3.89 + 4.90 days, while for the patients who did not develop (187 patients; 19.8%) was 2.79+3.31 days (P <0.001). The majority of the patients (648; 68.7%) was hospitalized due to acute coronary syndromes (ACS), while 295 (31.3%) patients hospitalized due to other cardiac diseases. The mean cost for the first group of patients (ACS) was 94.15 EUR while for the second was 95.69 EUR. Gender, smoking, hypertension, diabetes mellitus, hyperlipidemia, and left ventricular ejection fraction did not have a statistically significant impact on the total medication cost. However, increased creatinine levels and age were associated with prolonged CICU hospitalization and higher medication cost. More specifically, each year of age increased the medication cost by 0.32 EUR (p=0.014). Conclusions The development of sustained cardiac arrhythmias, creatinine level and age were the most important factors, which influenced the duration of hospitalization and the total medication cost.