The pooled ORs suggested that the CTLA-4 49A/G polymorphism was significantly associated with NHL risk (AA vs. GA+GG: OR = 1.98, 95% CI = 1.68-2.32, P = 0.001), multiple myeloma risk (AA vs. GA+GG: OR = 1.60, 95% CI = 1.08-2.36, P = 0.018; GG vs. AA: OR = 0.60, 95% CI = 0.37-0.99, P = 0.045; GA vs. AA: OR = 0.64, 95% CI = 0.42-0.96, P = 0.031; G vs. A: OR = 0.76, 95% CI = 0.60-0.98, P = 0.032), and leukemia risk (AA vs. GA+GG: OR = 2.91, 95% CI = 1.22-6.95, P = 0.016). This evidence concerns the gene CTLA4 and non-Hodgkin lymphoma.