Introduction: Rhythmic auditory stimulation (RAS) has been shown to improve gait parameters in several neurological diseases, both in walk-training interventions and in one-time walking tests, but the effect in myasthenia gravis (MG) is unknown. Objective: The aim of this study was to examine if RAS improves walking distance and gait speed in patients with generalised myasthenia gravis (gMG) in the 6-minute walk test (6MWT). Methods: Forty-eight patients with gMG walked two 6MWTs under different conditions: (1) walking with RAS with a frequency of 100% of the patient’s fastest gait speed, (2) walking with RAS with a frequency of 110% of the patient’s fastest gait speed, or (3) walking in silence. Results: RAS with a frequency of 110% of the patient’s fastest gait speed increased the walking distance by 8.3 metres in the 6MWT vs standard 6MWT (p = 0.01), without increasing average walking heart rate (HR) or Borg scores. Conclusions: This study indicates that RAS may improve gait speed and walking distance in patients with gMG without additional exertion as judged by HR and Borg scores. Based on these results, RAS could be used as part of a physical rehabilitation program for patients with gMG.