The colonization of lymph nodes after i.v. infection with L. monocytogenes has been ignored so far, although it is known that such bacteria are able to infect lymph nodes after subcutaneous [59] or oral application [36] . Here we have shown that Listeria monocytogenes successfully colonizes cervical and inguinal lymph nodes also after i.v. infection. We noticed lymph node colonization due to the activation of the IFN-b reporter in such tissues. This impressively demonstrates the importance of using reporter systems that allow holistic unbiased observations. Colonization of lymph nodes could have taken place via dissemination of bacteria from the ''classical'' target organs spleen and liver. The delayed production of IFN-b in such organs would be in agreement with this notion. However, production of IFN-b correlated with the number of bacteria found in the colonized lymph nodes, which also showed a delayed increase. Thus, lymph nodes obviously are also primary target organs for L. monocytogenes, although they do not show the same penetrance as spleen and liver.