INTRODUCTION: Aesthetic breast area improvements for gynecomastia and gender dysphoria patients who seek a more masculine appearance have increased recently. We present our clinical experience in breast masculinization and a classification for these patients. METHODS AND MATERIALS: From July 2003 to May 2014, 68 patients seeking a more masculine thorax underwent surgery. They were divided into five groups depending on three factors: excess fatty tissue, breast tissue, and skin. A specific surgical treatment was assigned according to each group. The surgical treatments included thoracic liposuction, subcutaneous mastectomy, periareolar skin resection in one or two stages, and mastectomy with a nipple areola complex graft. The evaluation was performed 6 months after surgery to determine the degree of satisfaction and presence of complications. RESULTS: Surgery was performed on a total of 68 patients, 45 male and 22 female, with ages ranging from 18 to 49 years, and an average age of 33 years. Liposuction alone was performed on five patients; subcutaneous mastectomy was performed on eight patients; subcutaneous mastectomy combined with liposuction was performed on 27 patients; periareolar skin resection was performed on 11 patients; and mastectomy with NAC free grafts was performed on 16 patients. The surgical procedure satisfied 94% of the patients, with very few complications. CONCLUSIONS: All patients who wish to obtain a masculine breast shape should be treated with only one objective regardless patient's gender: to obtain a masculine thorax. We recommend a simple mammary gland classification for determining the best surgical treatment for these patients LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .