Aim of study: The aim of the study was to examine the levels of HDL and HDL / total cholesterol in all patients hospitalized in the Department of Heart and Vascular Diseases of the University Hospital Centre Osijek in a period of one month. The aim was also to examine the interdependence between HDL (and HDL / total cholesterol) concentrations and categories of cardiac diagnoses as well as to examine the relationship between HDL (and HDL / total cholesterol) concentrations and the therapy that patients are taking and other relevant clinical characteristics of patients. Study design: cross-sectional study Participants: Participants are hospitalized patients, divided into groups depending on the dominant diagnosis, other diagnoses, depending on whether they are taking statin therapy or not, whether they have low or normal ejection fraction of left ventricul. Materials and methods: The following data were collected in the archives of the hospital information system: demographic data (sex, age), laboratory findings: HDL-cholesterol concentration, HDL-cholesterol / total cholesterol ratio, AST, ALT, erythrocytes, hemoglobin, urea and creatinine. Clinical data: left ventricular ejection fraction, dominant and other diagnoses, therapy. Results: HDL-cholesterol levels are lower in all patients, HDL-cholesterol / total cholesterol levels were normal. Patients divided into the groups of basic diagnoses had different levels of HDL-cholesterol/total cholesterol. Divided into groups with other diagnoses all have low HDL-cholesterol levels accept group with hypothyreosis, levels of HDL-c holesterol/total cholesterol levels were normal. People on statin therapy have a higher HDL-cholesterol/total cholesterol value. Conclusion: HDL-Cholesterol levels are lower in all patients regardless of gender. The HDL-cholesterol/total cholesterol ratio is different between subjects groups of dominant diagnoses. Patients taking statin therapy had higher HDL-cholesterol/total cholesterol ratio levels compared to those who did not.