Abstract: The aim of this study was to investigate the antiproliferative proteins that probably have a role in Helicobacter pylori evade of immune response and cause chronic infection disease and also to see if coccoid form had a role in its chronicity. H. pylori strain VacA s2/m2 positive and CagA negative, from a gastric biopsy of a patient with peptic ulcer disease, was isolated and cultured in brucella agar. Both spiral and coccoid forms were harvested and ruptured by sonication. The cytoplasmic solutions of both forms were collected and their fractions obtained by gel chromatography and preparative polyacrylamide gel electrophoresis. The fractions were analyzed by MTT assay for their antiproliferative activity. We isolated two proteins with a significant dose dependent antiproliferative activity that analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis, one of them that was urease positive showed two bands with 61 and 27 kDa, which is resumed to urease of H. pylori, another consist of 57 and 63 kDa. Helicobacter pylori secret some proteins like urease that inhibit immune cells proliferation response against its antigens.