Background: Previous studies show positive effect of music on reducing anxiety, pain, and medication requirement. Anxiety has become a more pertinent issue in the intensive care unit (ICU) since wakefulness is preferred according to recent guidelines. Nevertheless, evidence on the effect of music in ICU patients is scarce. Therefore, we studied the effect of music intervention on anxiety in ICU patients.Methods: A multicentre randomized clinical trial was conducted between August 2020 and December 2021 in ICU’s at an academic medical center and two regional hospitals. Adult critically ill patients were eligible when hemodynamically stable and communicable (Richmond agitation-sedation scale (RASS) of at least -2). Patients in the intervention arm were offered music twice daily during three days for at least 30 minutes per session. Patients in the control group received standard care. The primary outcome was anxiety level assessed with the visual analogue scale for anxiety [VAS-A; range 0-10] twice daily (morning and evening). Secondary outcomes included; 6-item state-trait anxiety inventory (STAI-6), sleep quality, delirium, heart rate, mean arterial pressure pain, RASS, medication, ICU length of stay, patients’ memory and experience of ICU stay. Results: 94 patients were included in the primary analysis. Music did not significantly reduce anxiety (VAS-A in the intervention group; 2.5(IQR 1.0-4.5), 1.8(0.0-3.6), and 2.5(0.0-3.6) on day 1,2, and 3 versus 3.0(0.6-4.0), 1.5(0.0-4.0), and 2.0(0.0-4.0) in the control group; p>0.92). Overall median daily VAS-A scores ranged from 1.5 to 3.0. Fewer patients required opioids (21 vs. 29, p=0.03) and sleep quality was lower in the music group on study day one (5.0(4.0-6.0) vs. 4.5(3.0-5.0), p=0.03). Other outcomes were similar between groups. Conclusions: Anxiety levels in this ICU population were low, and music did not decrease anxiety. This study indicates that efficacy of music is context and intervention-dependent, given previous evidence showing decreased anxiety. Trial Registration number: Netherlands Trial Register: NL8595, Registered, 1 April 2020ClinicalTrials.gov ID: NCT04796389, Registered retrospectively, 3 April 2021