Transgender feminism, more popularly termed as transfeminism, is a feminist line of thought and practice which discusses and criticizes the morphological subordination of gender (as psychosocial construction) to sex (as biology), with theoretical and political repercussions on the bodies. This article identifies, through critical analysis, the theoretical foundations of transfeminism in the historical process of political consciousness and resistance, from readings which orientate academics and activists, constituted by the black feminism and other lines of feminist thought; recognizing and pointing out to the multiple contributions of diverse guidelines. The conclusion is that the fundamental elements that determine and guide transgender feminism are: the redefinition of the match between gender and biology, the reiteration of the interactional character of the oppressions, the recognition of stories of struggle for free gender expression and the validation of contributions from any individuals for the transfeminist thought and action, regardless of their gender identification.