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[en] Objective: To evaluate the percentage of I and II axillary levels receiving 45 Gy during adjuvant radiotherapy for breast cancer and correlate it with anatomical and planning variables. Methods: A retrospective study of 51 patients with breast cancer who received adjuvant external radiotherapy in breast or breast bed with tridimensional conformal technique during January 2008 to July 2013. Axillary levels were contoured according to the breast cancer atlas of Radiation Therapy Oncology Group (RTOG). The percentage of each axillary level that received 45 Gy (V45) was reviewed using the dose volume histogram (DVH). This was correlated with the surgery performed, the Clinical Target Volume (CTV), axillary volume, anteroposterior (APD) and laterolateral diameters (LLD) of chest, body mass index (BMI), gantry’s angle, distance between the input and output (DIO) of the radiation beam in chest, and patient position (ramp incline, height and angle of the arm). Results: The average V45 for level I and II was 44% (0 to 97.2%) and 17.7% (0 to 93.6%). The average dose in 95% of level I was 11.2 Gy (0.14-46.4 Gy) and 5 Gy (0.13-44.4 Gy) in level II. Variables with significant correlation to V45 of level I were the ramp incline (p<0.001) and DIO (p<0.019) and the ramp incline with level II V45(p= 0.004) in multiple univariate analysis. Ramp incline, DIO and LLD correlate with V45 of level I in multivariate analysis (p= 0.012, p= 0.007, p= 0.012, respectively). Patients with BMI>25 received higher doses in level I (p=0.026). Conclusion: Axillary coverage with 45 Gy during adjuvant breast irradiation is not adequate but appear to increase with a larger ramp incline and bigger DIO. Dose in Level I increases with BMI>25 although remains unsatisfactory. (author)