The goal of this study was to evaluate the rate of seromas after axillary dissection or sentinel lymph node biopsy. This is a prospective study based upon a series of 229 patients. Among those 229 patients, 179 had an axillary dissection and 50 had a sentinel lymph node biopsy. In the axillary dissection group, 40% of patients developed a seroma. The maximum number of aspirations needed was 8. In the sentinel lymph node group, 18% of patients developed a seroma that never recurred after a single aspiration. Seromas are still a very frequent complication after axillary dissection. The sentinel lymph node biopsy has helped to reduce the rate of axillary seroma, and the number of aspirations needed to evacuate them.