Background: A limited number of studies suggest a prevalence of periodontal pathogens in patients with rheumatoid arthritis (RA); however, results are inconsistent. The aim of this study is to investigate clinical periodontal and microbiologic parameters in patients with RA.Methods: Sixty‐six patients with RA, aged 49.5 ± 8.4 years, participated in the study. The periodontal classification was assessed with the periodontal screening index (PSR/PSI) allocated to the following parameters: 1) healthy; 2) gingivitis (PSR/PSI score 0 to 2, maximum one sextant score; 3) moderate periodontitis (>1 sextant PSR/PSI score 3, maximum one sextant score; or, 4) severe periodontitis (>1 sextant PSR/PSI score 4). Pool samples were taken for microbiologic (polymerase chain reaction) analysis for the presence of 11 periodontal pathogens. Statistical analysis was by non‐parametric analysis of covariance.Results: No patients were periodontally healthy: 24 patients were classified as having gingivitis; 18 patients had moderate periodontitis; 23 patients had severe periodontitis; and one patient was toothless. For most patients, Fusobacterium nucleatum (98%), Eikenella corrodens (91%), and Parvimonas micra (previously Peptostreptococcus micros; 88%) were above the detection threshold. Strong periodontal pathogens were less frequently detected: Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans, 16%); Porphyromonas gingivalis (58%); and Tannerella forsythia (previously T. forsythensis, 78%). Statistical analysis showed no significant influence of rheumatic factor (P = 0.33) on periodontal classification and on microbiologic parameters (P >0.05). Only smoking showed a significant influence (P = 0.0004) on the periodontal classification and in the case of E. corrodens (P = 0.02).Conclusions: Most patients with RA in this study showed moderate‐to‐severe periodontitis and the presence of periodontal pathogens. No association was found between rheumatic factor on periodontal classification and microbiologic parameters.