In immunosuppressed or autoimmune disease states, disordered immune responses may lead to non-Hodgkin's lymphoma (NHL). In a US population-based case-control study of NHL (1998-2000), the authors collected personal histories of immune-related conditions and use of immune-modulating therapies as well as family histories of autoimmune conditions. The study included 1,321 NHL cases and 1,057 controls; only half received some questionnaire components. NHL was associated with Sjögren's syndrome (odds ratio (OR) = 13, 95% confidence interval (CI): 1.7, 100) and lupus (OR = 4.2, 95% CI: 1.2, 15). Two specific NHL subtypes were strongly associated with Sjögren's syndrome: salivary gland (OR = 290, 95% CI: 33, 2600) and marginal zone (OR = 75, 95% CI: 9.1, 610). NHL was less convincingly associated with receipt of an organ transplant (OR = 2.0, 95% CI: 0.4, 11). Other autoimmune conditions were too rare to evaluate or not associated with NHL. Corticosteroid use was unrelated to NHL (OR = 1.0, 95% CI: 0.8, 1.2), but methotrexate use was marginally associated (OR = 2.3, 95% CI: 0.7, 7.5). Family history of dermatomyositis was associated with NHL (7 cases vs. 0 controls, OR = infinite; two-sided p = 0.02), but dermatomyositis was absent in cases themselves. Family history of remaining conditions was unrelated to NHL. Results suggest that disordered immunity in some immune-related conditions can lead to NHL.