Background: Balance impairment in Parkinson's disease (PD) improves only partially with dopaminergic medication. Therefore, non-pharmacological interventions such as physiotherapy are important elements in clinical management. External cues are often applied to improve gait, but their effects on balance control are unclear. Objective/Methods: We performed a prospective, single-blind, randomized clinical trial to study the effectiveness of balance training with and without rhythmical auditory cues. We screened 201 volunteers by telephone; 154 were assigned randomly into three groups: (1) multimodal balance training supported by rhythmical auditory stimuli (n = 56) (RAS-supported multimodal balance training); (2) regular multimodal balance training without rhythmical auditory stimuli (n = 50); and (3) control intervention involving a general education program (n = 48). Training was performed for 5 weeks, two times/week. Linear mixed models were used for all outcomes. Primary outcome was the Mini-BESTest (MBEST) score immediately after the training period. Assessments were performed by a single, blinded assessor at baseline, immediately post intervention, and after one and 6-months follow-up. Results: Immediately post intervention, RAS-supported multimodal balance training was more effective than regular multimodal balance training on MBEST (difference 3.5 (95% Confidence Interval (CI) 2.2; 4.8)), p < 0.001). Patients allocated to both active interventions improved compared to controls (MBEST estimated mean difference versus controls 6.6 (CI 5.2; 8.0), p < 0.001 for RAS-supported multimodal balance training; and 3.0 (CI 2.7; 5.3), p < 0.001 for regular multimodal balance training). Improvements were retained at one-month follow-up for both active interventions, but only the RAS-supported multimodal balance training group maintained its improvement at 6 months. Conclusion: Both RAS-supported multimodal balance training and regular multimodal balance training improve balance, but RAS-supported multimodal balance training-adding rhythmical auditory cues to regular multimodal balance traininghas greater and more sustained effects.