It has been reported that interleukin-1beta (IL-1B) genes play a crucial role in the genetic predisposition to gastric cancer although there is no information about their role in different subtypes of gastric cancer. We performed single nucleotide polymorphism analysis of IL-1B in 241 gastric cancers including early onset gastric cancers (EOGC), conventional gastric cancers, and gastric stump cancers (GSCs) as well as 100 control patients, using real-time polymerase chain reaction and sequence analysis. The C allele was present in 60% of EOGCs, 59% of conventional gastric cancers, and 90% of GSCs, compared to 62% in the control group. Interestingly, there was no difference between early onset and conventional gastric cancer with respect to the IL-1B -31T>C polymorphism distribution. A statistically significant difference in the presence of the C allele compared to the control group was found in patients with gastric stump cancer (p = 0.008) with the T allele conferring protection against gastric stump cancer. In summary, we have shown that the IL-1B -31C allele promoter polymorphism is significantly associated with gastric stump cancer compared to the control group. Although several molecular differences have been identified between conventional gastric cancer and early onset gastric cancer, the IL-1B -31 allele distribution is similar between these two groups.