Kaposi sarcoma-associated herpes virus (KSHV) infects B-cells and is found in non-Hodgkin lymphoma (NHL) B-cell tumors and could therefore contribute to the occurrence of NHL. We performed a nested case-control study including 155 incident NHL cases and matched noncancer controls. Pre-NHL serum was tested for KSHV DNA and antibodies. Serum KSHV DNA was more common in cases than controls (14% versus 6%, P = 0.03), but after adjustment, the difference was not significant. Epstein-Barr virus serum DNA was similarly unassociated with NHL as were KSHV antibodies. KSHV is not a primary cause of NHL in HIV-infected men who have sex with men.