Objective: To establish normative data on the width of the acromioclavicular (AC) joint space using sonography, based on a selected Nigerian cohort without any shoulder injury or pathology. Materials and Methods: A cross-sectional study was conducted on the normal AC joints of randomly selected Nigerians. A sonographer performed the examination and obtained all the width measurements of AC joint space, using a GE LOGIQP6 ultrasound system and a multiple-frequency linear transducer. Results: The width of the AC joint space was equal on both sides, measuring 5.6 ± 1.2 mm for the right and 5.6 ± 1.2 mm for the left ( P = .701). The mean width of both joint spaces differed between men and women, with the men having a wider space ( P < .05). Age had a strong negative predictive relationship, with the AC joint space width and both joint spaces decreasing with age ( P < .001). Weight and body mass index had weak negative predictive relationships with both joint space widths ( P < .001). Participant height had a very weak positive predictive relationship with both joint space widths ( P < .05). Conclusion: Normative data on the width of the AC joint space, in a randomly selected Nigerian cohort, are provided and may be clinically useful in the ongoing sonographic assessment of the AC joint.