While a familial predisposition may exist in up to 20% of patients with Waldenström's Macroglobulinemia (WM), the precipitating cause of this B-cell malignancy remains unknown in most patients. In previous studies, an association between hepatitis C virus (HCV) infection and WM has been suggested as etiological. This relationship has been the subject of debate, however, with some studies demonstrating increased incidence of HCV infection among WM patients and other studies showing no such association exists. This discordance might be attributable to the analytical method used, HCV antibody detection, which might be ineffective in patients with immunosuppression. We therefore analyzed the prevalence of HCV in a large population of WM patients utilizing both an HCV antibody detection immunoassay as well as qualitative polymerase chain reaction assay to directly detect HCV presence in serum samples. None of 100 randomly tested WM patients in this study tested positive for HCV by either analytical method. Our results therefore demonstrate a lack of association between HCV and WM.