AIM: To find out if a functional promoter polymorphism in the IL-8 gene along with cagA status and polymorphisms in vacA gene influence the type of diseases in Iranian patients infected by H pylori. METHODS: IL-8 -251 A/T polymorphism was genotyped by oligonucleotide allele specific PCR (ASO-PCR) in a sample of 233 patients with H pylori infection undergoing upper gastrointestinal endoscopy. The presence of cagA gene and polymorphisms in vacA gene was also determined by PCR. Association of these genetic polymorphisms with the development of gastritis, peptic ulcers as well as gastric cancer was tested. RESULTS: When the patients with different clinical manifestations were compared according to the presence of cagA gene or various vacA genotypes, only the vacA genotypes were significantly different among gastritis, peptic ulcer and gastric cancer patients (x2= 17.8; P=0.001). Furthermore, there was a significant difference in the frequency of IL-8 -251 A/T genotypes between patients with gastric cancer and benign diseases (x2= 10.47; P = 0.005). CONCLUSION: The IL-8 -251 A/T polymorphism and the polymorphisms in H pylori vacA gene are involved in limiting the infection outcome to gastritis and peptic ulcer or in favoring cancer onset in Iranian patients. AIM: To find out if a functional promoter polymorphism in the IL-8 gene along with cagA status and polymorphisms in vacA gene influence the type of diseases in Iranian patients infected by H pylori. METHODS: IL-8 -251 A / T polymorphism was genotyped by oligonucleotide allele specific PCR (ASO-PCR) in a sample of 233 patients with H pylori infection undergoing upper gastrointestinal endoscopy. The presence of cagA gene and polymorphisms in vacA gene was also determined by PCR. Association of these genetic polymorphisms with the development of gastritis, peptic ulcers as well as gastric cancer was tested. RESULTS: When the patients with different clinical manifestations were compared according to the presence of cagA gene or various vacA genotypes, only the vacA genotypes were significantly different among gastritis, peptic ulcer and gastric cancer patients (x2 = 17.8; P = 0.001). Furthermore, there was a significant difference in the frequency of IL-8 -251 A / T genotypes between patients wit CONCLUSION: The IL-8 -251 A / T polymorphism and the polymorphisms in H pylori vacA gene are involved in limiting the infection outcome to gastritis and peptic ulcer or in favoring cancer onset in Iranian patients.