PURPOSE: This study aimed to determine the effect of music therapy on pain, anxiety, agitation, and sedation levels in patients hospitalized in the cardiac intensive care unit following coronary angiography. METHOD: The study was conducted in a parallel randomized controlled experimental model with patients treated in the Cardiac Intensive Care Unit of a hospital in Eastern Turkey. Sixty patients with coronary angiography were randomly assigned to the experimental (n = 30) and control (n = 30) groups. "Personal Data Form," "Pain Visual Analog Scale (Pain-VAS)," "Anxiety Visual Analog Scale (Anxiety-VAS)" and "Richmond Agitation and Sedation Scale (RASS)" were used for data collection. Chi-square, independent/dependent samples t-test, and repeated measures ANOVA were used to analyze the data. RESULTS: It was determined that the decrease in pain, anxiety, agitation and sedation levels of the patients in the experimental group was statistically significant (p ≤ .001). The changes in the control group were insignificant. It was determined that music therapy application had a significant, and large effect of 70.4% on pain, 64.6% on anxiety, and 72.2% on agitation and sedation. CONCLUSION: Music therapy has been found to reduce pain, anxiety, agitation, and sedation in patients after coronary angiography, demonstrating a broad effect. It is recommended that music therapy be used as a nursing practice in the intensive care unit.