Background: Mastectomy is an essential part of gender reassignment surgery for female-to-male transgender patients. Available studies indicate high patient satisfaction within this patient group; however, a standardised evaluation procedure is yet to be established., Method: Based on the BREAST-Q questionnaire, we developed a modified version targeting issues concerning FM patients; hence, all questions focussing on the physiology of biologically female patients were removed or tailored to address more specific transgender issues. Post-mastectomy transgender male patients from 1991 until 2017 were contacted and evaluated based on the questionnaire. This questionnaire comprises a total of 57 questions regarding general satisfaction with the ches area, as well as specific questions regarding satisfaction with the nipple-areola complex (NAC) and topics regarding expectations, regrets, self-confidence and sex life after mastectomy., Results: Overall, we found a high level of patient satisfaction after mastectomy. The level of regret was low and all patients would repeat mastectomy if needed., Conclusion: For most transgender males, mastectomy plays an essential role in gender reassignment surgery, overall leading to an improved quality of life for this patient population., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)