Joint lavage for knee osteoarthritis is an invasive procedure that can be stressful and painful. We aimed to assess the impact of music therapy on perioperative anxiety, pain and tolerability of the procedure in patients undergoing joint lavage performed with two needles. We randomized all patients diagnosed with knee osteoarthritis and undergoing joint lavage in our department from November 2009 to October 2010 to an experimental group listening to recorded music or a control group receiving no music intervention. Perioperative anxiety and pain related to the procedure were self-reported on a visual analogic scale (0-100 mm visual analog scale [VAS]), and heart rate and blood pressure were measured during the procedure. Tolerability was assessed on a four-grade scale directly after the procedure. We included 62 patients (31 in each group). Mean age was 68.8 ± 12.6 years (72% females). As compared with the control group, the music group had lower levels of perioperative anxiety (40.3 ± 31.1 vs. 58.2 ± 26.3 mm; p = 0.046) and pain related to the procedure (26.6 ± 16.2 vs. 51.2 ± 23.7 mm; p = 0.0005). Moreover, heart rate was lower in the music group (69.5 ± 11.4 vs. 77.2 ± 13.2; p = 0.043) but not diastolic or systolic blood pressure. Tolerability was higher in the music group (p = 0.002). Music is a simple and effective tool to alleviate pain and anxiety in patients undergoing joint lavage for knee osteoarthritis.