Dilated canine hearts were used to teach undergraduate students internal and external cardiac anatomy. The specimens were dilated using hydrostatic pressure and then fixed using 5% formalin. These specimens provided the students with an alternative to prepackaged embalmed hearts and anatomical models for studying the external and internal cardiac anatomy. In addition, the dilated hearts are more similar to the organ they encounter within the thoracic cavity of their dissected animal. This gives the students a better chance of developing a three-dimensional understanding of the heart. (Contains 4 figures.)