Numerous studies have shown that subinhibitory concentrations of antimicrobials can alter bacterial virulence factors. This study evaluates motility and biofilm formation by H. pylori 43504 grown in subinhibitory concentrations of amoxicillin (AMX), clarithromycin (CLA), or tetracycline (TET). For the swimming and swarming motility assays, H. pylori 43504 suspensions were prepared with the strain alone or with the strain in AMX, CLA, or TET at ½ MIC. Next, the media were incubated at 37 ºC, under microaerophilia. To assess biofilm formation in the presence of one of the antimicrobials at subinhibitory antimicrobial concentrations, bacterial suspensions (109 CFU/mL) were prepared in 2.5% FBS containing AMX, CLA, or TET at ½ MIC.  After incubation for 10 days, H. pylori 43504 grown in medium containing AMX, CLA, or TET at ½ MIC presented greater swimming motility and lower swarming motility than the non-treated strain. H. pylori 43504 grown in medium containing AMX, CLA, or TET at ½ MIC showed stronger biofilm production than the non-treated strain. Our results showed that AMX, CLA, or TET at subinhibitory concentrations favors H. pylori 43504 swimming motility and biofilm formation after incubation for 3 days. This may have clinical consequences and make the microorganism difficult to eradicate.