An outbreak of rectal lymphogranuloma venereum (LGV) has been reported since 2003 in men who have sex with men, most of them being infected with human immunodeficiency virus. In these patients, unusual clinical presentations such as rectal tumor or intense lymphoproliferation on rectal biopsies may lead to an erroneous diagnosis of aggressive non-Hodgkin lymphoma. Three patients were referred to our center for the management of rectal B-cell non-Hodgkin lymphoma on the basis of a rectal pathologic specimen showing intense lymphoproliferation, the very suspect of lymphoma. Because of anamnesis of anal intercourses and venereal diseases, additional study revealed that all 3 had a positive Chlamydia trachomatis polymerase chain reaction on the rectal biopsy specimen. Rectal LGV was therefore considered and successfully treated with antibiotics. We propose that all patients presenting with a suspected rectal lymphoma should have a careful anamnesis of sexual behavior and a specific detection of C. trachomatis using polymerase chain reaction analysis on biopsy specimen to rule out the possibility of rectal LGV.