The aim of this study was to evaluate if the presence of periodontal infections (PI) is associated with community-acquired pneumonia (CAP) in a group of patients admitted to a hospital. A total of 140 patients were enrolled in this case–control study, with 70 patients having CAP (case group) and the other 70 patients diagnosed with other systemic diseases (control group). A periodontal examination was carried out to assess pocket probing depth (PPD), clinical attachment loss (CAL), bleeding on probing (BOP), and presence of bacterial plaque (BP). CAL and BOP showed higher scores in the case group over the control group. They were, respectively, 3.16 ± 2.43 mm and 0.33 ± 0.24 % for the case group, and 1.99 ± 2.23 mm and 0.25 ± 0.24 % for the control group ( p  < 0.05). High scores for BP were observed in both groups (case: 97.1 %; control: 98.6 %, p  = 1.0000). Chronic periodontitis (CP) was more frequent in patients with CAP (case: 61.4 %; control: 41.4 %). The presence of moderate or severe CP increased the risk for CAP odds ratio (OR) = 4.4, 95 % confidence interval (CI) = 1.4–13.8, even when adjusted for age, ethnicity, gender, and smoking. Moderate and severe chronic periodontitis were associated with CAP in this study.