BACKGROUND: Multiple options of genital gender-affirming surgery are available to transmen. The transman should be able to weigh these options based on the outcomes, risks, and consequences that are most important to him. For this reason, a decision aid for genital surgery in transmen (DA-GST) was developed. It aims to support the transman in making thoughtful choices among treatment options and facilitate shared decision-making between the healthcare professionals and the transindividual. AIM: The aim of this study was to evaluate the newly developed DA-GST. METHODS: This was a cross-sectional study using mixed methods. Transmen considering to undergo genital surgery were eligible to partake in the study. The questionnaires used in this study were developed by adapting the validated Dutch translation of the "Decisional Conflict Scale," the "Measures of Informed Choice," and the "Ottawa Preparation for Decision-Making Scale." Qualitative interviews were conducted querying their subjective experience with the DA-GST. The data from the questionnaires were statistically analyzed, and the data from the interviews were thematically analyzed. OUTCOMES: The main outcome measures were decisional conflict and decisional confidence measured via self-report items and qualitative data regarding the use of the DA-GST via interviews. RESULTS: In total, 51 transmen participated in the questionnaires study, 99 questionnaires were analyzed, and 15 interviews were conducted. Although confident in their decision, most transmen felt responsible to collect the necessary information themselves. The ability to go through the decision aid independently aided the decision-making process by providing information and highlighting their subjective priorities. Suggested additions are pictures of postoperational outcomes and personal statements from experienced transmen. CLINICAL TRANSLATION: The DA-GST could be implemented as an integral part of transgender health care. Clinicians could take the individual personal values into account and use it to accurately tailor their consult. This would ultimately improve the doctor-patient relationship and decrease decisional regret by enhancing effective shared decision-making. STRENGTHS & LIMITATIONS: This mixed-method design study confirmed the use of the DA-GST while taking a broad range of decisional factors into account. Limitations include the absence of a baseline analysis and the limited power for the comparison of treatment groups. CONCLUSIONS: This study suggests that the DA-GST helped transmen feel more prepared for their personal consult with the surgeon, reduced decisional conflict, and increased their decisional confidence. Mokken SE, Özer M, van de Grift TC, et al. Evaluation of the Decision Aid for Genital Surgery in Transmen. J Sex Med 2020;17:2067-2076.