Lymphangiograms were made in dogs with experimental congestive heart failure by cannulation of the left cardiac efferent (LCE), left pulmonary efferent (LPE), or cardiopulmonary lymphatic and injection of radiopaque medium. The lymphoangiograms showed cardiac enlargement and dilated mediastinal lymphatic channels consistent with an increase in lymph flow. By consecutive injections in the LCE and LPE, wer demonstrated that a common channel, the cardiopulmonary lymphatic, is opacified by injection in either the LPE or LCE. This common channel has been called the "cardiac lymphatic" and used for the collection of "cardiac" lymph. The authors' experiments suggest that this cardiopulmonary lymphatic carries both cardiac and pulmonary lymph.