When stressed, bacteria can enter various nondividing states. In the present study, nondividing filamentous form in Helicobacter pylori was induced by a beta-lactam antibiotic, aztreonam. In order to find possible cell division checkpoints in H. pylori, 2-DE was used to compare the proteomic profile of nondividing filamentous H. pylori with its spiral form. In total, 21 proteins involved in various cellular processes showed differential expression. One protein induced by aztreonam was a cell division inhibitor (minD), related to cell division. We then constructed the deletion mutant of minD in H. pylori 26695. Scanning electron microscope observation showed that the deletion of this protein provoked some bacteria to change into a short rod-shape and the viability of the mutant is lower than that of the wild type. Moreover, sequence comparison showed that minD of H. pylori and that of Escherichia coli share 50 % amino acid identity. This suggested that this protein possibly plays the similar part in H. pylori as in E. coli.