Objective: To evaluate the repeatability and reproducibility of an ultrasound examination of the acromioclavicular joint (ACJ) performed by an orthopaedic surgeon to analyze anterior ACJ relationship in the horizontal plane. Design: Prospective observational study on healthy subjects. Setting: The study was conducted in 2017 in a university department of orthopaedic surgery and traumatology. Level of Evidence: III. Patients (or Participants): Forty consecutive volunteers aged 18 to 40 years were involved. Interventions (or Assessment of Risk Factors or Independent Variables): The ultrasound examination was performed by 2 orthopaedic surgeons with a SonoSite M-Turbo portable ultrasound machine (Fujifilm, Japan). Distance measurement between the anterior edge of the clavicle (AECL) and the anterior edge of the acromion (AEAC) was done on the right side, then on the left one and repeated by the same examiner. Main Outcome Measures: The intra- and interexaminer reproducibility of measurements was analyzed as primary outcome. Concordance of distance measurements between the right and left sides on the same subject was evaluated, as well as the “typical morphology” of the ACJ in the horizontal plane. Results: The intra- and interexaminer reproducibility for AECL-AEAC distance measurements was, respectively, 0.95 (0.93-0.97) and 0.87 (0.84-0.90). The correlation between the right and left sides was significant (P < 0.001), with a reproducibility of 0.86 (0.83-0.89). Twenty-seven (67.5%) volunteers were considered to have a “perfect alignment” of the AECL and AEAC. Conclusions: This study confirms that it is possible to evaluate with good reproducibility the anterior AC relationship in the horizontal plane and that both sides are similar on the same subject.