The heart is one of the first organs to develop during the embryogenesis. While heart development is not the result of a single molecular pathway, the bone morphogenetic protein (BMP) pathway has earned relevance over its influence on heart formation. Recent studies demonstrate that BMPs and their receptors are likely to be extremely important players involved in the creation and differentiation of the primary heart-forming regions, heart tube formation, elongation, looping, septation and valvulogenises. In general, myocardial BMPs bind to endocardial BMP receptors to activate a signaling cascade that culminates in the production of cardiac-related proteins. Of the different BMP receptors known to date, Alk2 is one of the most influential in heart development. Alk2 transcripts have been mapped to regions where anatomical heart structures arise, and their ablation has consequences remarkably more severe than those of ablation of other tested BMP receptors. However, despite their importance, no expression studies have yet been performed. In this study, we sought to determine the localization of Alk2 proteins via immunohistochemistry. Our results demonstrate that, in an embryo that is approximately 80 hr old, Alk2 proteins are preferentially expressed around the outflow tract, the developing endocardial cushions, throughout the septum primum, and possibly scattered throughout the embryonic ventricle.