This article tried, from an intersectional standpoint, to grasp the challenges experienced by health professionals and service users of human milk banks in provision of care for transgender men chestfeeding. This exploratory, descriptive qualitative study drew on interviews of six human milk bank staff, who had previously assisted trans men in relation to chestfeeding and two bisexual trans men, who chestfed. The data was treated by thematic analysis, supported by Atlas.ti software, version 9.0. Lacunas in the educational, institutional and management spheres, associated with personal and social issues, reproduce a pre-conceived normative model and disregard the special demands of providing chestfeeding care for the trans population. Cisheteronormativity and “professional supremacy” operate in personal, social and institutional respects to segregate transgender men in lactation support services. Intersectional analysis of these challenges affords an overall view of segregative factors and enables public policies to be introduced to promote social justice.