Recent studies have suggested an association between periodontal disease and the presence of Herpesviruses, in particular: Epstein-Barr virus (EBV) and Human Cytomegalovirus (CMV) (Contreras et al., 1999--Contreras et al., 2000--Slots et al., 2000--Ting et al., 2000). In the work reported in this paper, we use a multiplex Polymerase Chain Reaction (PCR) to compare the presence of Herpesviruses and putative bacterial pathogens in patients with periodontal disease and in healthy individuals. Direct detection of microorganisms with PCR is shown to offer significant advantages in terms of time, effort and cost. The study detected no statistically significant differences between the prevalence of EBV and CMV in patients and controls. The failure to replicate previous findings may be due to differences in the age composition and the geographical and social origins of the study groups. The study detected a significant excess of HSV-1 in periodontal patients. This suggests that the role of Herpesviruses in the pathogenesis of periodontal disease deserves further investigation. The bacterial assay confirmed the results of previous studies showing a strong association between periodontitis and the presence of A. actinomycetemcomitans, P. gingivalis and P. intermedia.