Phonomyography (PMG) is a novel method to determine neuromuscular blockade (NMB) with high sensitivity and applicability at all muscles. The adductor pollicis muscle has long been used in research and clinical practice as reference for neuromuscular monitoring. The goal of our study was to compare PMG signals (train-of-four [TOF] ratios and T(1)/T(0) values) from both hands of the same patient to investigate the influence of hand dominance on neuromuscular monitoring. In 14 patients, PMG was recorded via small piezoelectric microphones taped over the thenar mass of both hands. After induction of anesthesia, both ulnar nerves were stimulated supramaximally using TOF stimulation every 12 s. Mivacurium 0.2 mg/kg was administered within 5 s. Onset, maximum effect, and offset of NMB were compared between both adductor pollicis muscles. Twelve patients were right-handed and two patients were left-handed. No statistical difference was found between the signals from the dominant or nondominant hand. Correlation was very good (r = 0.95). Agreement was excellent with a bias of -0.57% and limits of agreement of -17.9% to 16.7% (dominant - nondominant hand). This study shows minimal bias, good correlation and no statistical difference when NMB is monitored at both the dominant and nondominant adductor pollicis muscles. Both hands could be used interchangeably to assess NMB at the adductor pollicis muscle.