Background. The aim of the present study was to assess the immediate effects of auricular acupuncture (AA) on the electromyographic (EMG) activity of the upper trapezius muscle and pain in nonspecific neck pain (NS-NP) patients. Twelve patients with NS-NP (NS-NP group) and 12 healthy subjects (HS Group) were enrolled in a randomized, single-blinded, crossover study. Each subject received a single session of AA and sham AA (SAA). Surface EMG activity was measured in the upper trapezius muscle at different “step contractions” of isometric shoulder elevation (15%, 20%, 25%, and 30% MVC). The outcome measure in patients with NS-NP was based on the numerical pain rating scale (NRS). AA treatment led to a significant decrease in EMG activity in both groups (NS-NP group: p = 0.0001; HS group: p < 0.0001—ANOVA test). This was not the case for the SAA treatment (NS-NP group: p = 0.71; HS group: p < 0.54). Significant decreases (p < 0.001) in the NRS were found for both treatments (AA and SAA). This study demonstrated the immediate effect of auricular acupuncture on the electromyographic activity of the upper trapezius muscle but the effect of this intervention on pain symptoms in patients with nonspecific neck pain was inconclusive.