OBJECTIVES: The aim of this study was to examine individual and institutional variability in the results of coronary angiography. ----- METHODS: Results of 799 coronary angiographies performed in Merkur University Hospital were divided into groups based on the severity of the disease (normal coronary angiography, stenosis <50%, significant coronary disease), and the data on the referral were carried out for each of them. Individual and institutional differences were compared by the x2 test for each group, and p-values under 0.05 were considered significant. ----- RESULTS: Significantly less coronary angiographies showed no coronary disease if they were referred by invasive cardiologists rather than noninvasive cardiologists (p=0.046), whereas the findings of the patients that were hospitalized before the examination showed no coronary disease less frequently than the ones referred by either group of cardiologists (p=0.014; p=0.00009). Individual differences were found in the referral of patients with significant coronary disease, whereas institutional differences were found in all result groups. ----- CONCLUSION: Individual and institutional variability of the results of coronary angiography can be proven by analyzing the information provided by just one healthcare institution in Croatia. Further investigation should focus on prior noninvasive management and compare it with current guidelines. Similar research in other institutions would help analyze the results of invasive coronary angiography at a national level.