Limited evidence suggests the importance of inflammatory processes for the etiology of lymphomas. To further research in this area, we investigated the role of genetic variants in key inflammatory factors, non-steroidal anti-inflammatory drug [NSAID] use, and their joint effect in lymphomagenesis.The study comprised 710 case-control pairs, matched for gender, age, and study region. We examined the association of regular NSAID use and polymorphisms in prostaglandin-endoperoxide synthase-2 (COX2), prostaglandin E synthase (PTGES), interleukin-1 alpha (IL1A), IL-1 beta (IL1B), and IL-1 receptor antagonist (IL1RA), and lymphoma risk by applying logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CI).Regular NSAID use was associated with a slightly reduced risk of B-NHL (OR = 0.8, 95% CI = 0.6-1.1). For T-NHL, the COX2 rs2745557 A-allele conferred a 2.2-fold (95% CI = 1.1-4.5) and homozygosis for the IL1RN rs454078 T-allele was associated with a 4.5-fold (95% CI = 1.4-13.9) elevated risk, however, based on sparse data. IL1 haplotype 5 was associated with a statistically significant 43% increased risk for B-NHL among non-regular users of NSAIDs, but a 70% decreased risk for regular users (p-value for interaction < 0.001).These results suggest the relevance of joint effects between NSAID use and IL1 haplotypes on the risk of B-NHL.