An ongoing outbreak of lymphogranuloma venereum (LGV) L2b proctitis, predominantly in HIV-positive men who have sex with men (MSM), has been reported in industrialised countries. A case of reactive arthritis after L2b proctitis is described. This case expands the spectrum of severe complications related to LGV L2b proctitis. Since this infection may be asymptomatic, this organism should be screened for in HIV-positive MSM with symptoms consistent with reactive arthritis.