Purpose: To assess the relationship between periodontitis and nosocomial pneumonia in intensive care unit (ICU) patients. Materials and Methods: The present study was conducted in accordance with the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and registered (CRD42018105124) with PROSPERO (International prospective register for systematic reviews, University of York, York, UK). A search was conducted in five databases without restrictions regarding language or date of publication. From 560 studies selected, 10 underwent full-text analysis. Five studies were eligible (five case-control studies), and all were entered in the meta-analysis. Meta-analysis was performed with tests for sensitivity and statistical heterogeneity. Summary effect measures were calculated by odds ratio (OR) and 95% confidence interval (CI). Results: There was a significant association between periodontitis and nosocomial pneumonia in the meta-analysis (OR 2.55, 95% CI 1.68 to 3.86). In this meta-analysis, I2 = 0%. Conclusions: The evidence demonstrates a positive association between periodontitis and nosocomial pneumonia. Individuals with periodontitis admitted to the ICU were more likely to present nosocomial pneumonia than individuals without periodontitis.