To examine the antibacterial activity of diverse extracts of propolis harvested at winter and spring from several locations of Algarve, Portugal, against Gram-negative and Gram-positive bacteria was the main goal of the present work. For such, the antibacterial activity was determined by agar diffusion. The results showed that all tested bacterial strains showed susceptibility to diluted propolis extracts and in a dose-dependent manner. Two propolis samples collected at springtime showed higher antibacterial activity, in comparison with samples harvested at wintertime. Ethanolic and methanolic extracts have a very similar activity (P<0.05). Helicobacter pylori strains J99 and 26695 were the most susceptible strains to the tested extracts (33.67±2.52 mm and 35.67±0.58mm, respectively). This study constitutes the first approach of the biological activities of Portuguese propolis from the Algarve region and evidences its potential use to combat bacterial infections, in particular against the gastric pathogen H. pylori.