Methods are disclosed for lymphatic system imaging using dendrimer conjugates as contrast agents. The disclosed methods are applicable to the imaging of all lymphatic structures, but in particular embodiments are particularly suited for imaging specific parts of the lymphatic system such as lymph nodes or lymphatic vessels. The methods permit the assessment of abnormal conditions within the lymphatic system, such as lymphoma/lymphoproliferative disease, inflammation, and cancer metastasis. The methods also may be used to identify and locate lymph nodes into which lymph fluid flows from a tumor.