The present study aimed to measure the thickness of the subcutaneous adipose tissue (SAT) at the site of the surgical incision for axillary lymph node dissection (ALND) and to record potential anatomical variations in the medial cutaneous nerve of the arm (MCNA), the intercostobrachial nerve (ICBN), the lateral thoracic vein (LTV), the lateral thoracic artery (LTA) and the pectoral muscle pedicle (PMP), considering that some details of the anatomy of these structures within the axilla are still unclear.A prospective study was conducted in 100 consecutive patients with breast cancer who underwent ALND as part of surgical treatment. The anatomy of the dissected axilla was video recorded.The SAT thickness ranged from 8 mm to 60 mm, with an average thickness of 25.9 mm. A positive correlation was observed between the SAT thickness and the body mass index (BMI) of the evaluated patients (r = 0.68; p < 0.0001). The MCNA was the anatomical structure that was least commonly observed in the axilla (22% of cases), while the PMP was the most constant element, identified in 100% of cases. All of the studied anatomical structures observed within the axilla showed variation in at least one of the aspects analyzed, i.e., the point of entry and exit, path, number and location of divisions or branches.The present study demonstrated wide variation in thickness of the SAT overlying the axilla and identified the existence of broad normative anatomical variation of the axilla.