Background: Numerous studies point to an association between periodontal and cardiovascular diseases. The results, however, are not consistent. Genetic factors of host response and the influence of periodontal pathogens have not sufficiently been investigated although they might be responsable for the mentioned discepancies. The aim of this study was to examine the prevalence of periodontal pathogens and polymorphisms in the interleukin-1 (IL-1) gene cluster in patients after acute myocardial infarction (AMI). Material and Methods: In 54 patients with AMI (35-50 years) and 50 healthy probands (36-61 years) the following parameter were recorded: periodontal probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), plaque index (PI) and gingival index (GI). In all patients and controls subgingival plaque samples were analysed for periodontal pathogens Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf) and Prevotella intermedia (Pi) using dot blot hybridisation. Further, in 39 AMI patients and 50 controls allele frequencies of IL-1A, IL-1B and IL-1RN were examined using PCR with reverse hybridisation. Results: In patients with AMI all periodontal parameters (PD, CAL, BOP, PI, GI) were significantly higher than in healthy controls. Among different cut-off levels, the frequency of more than 50% sites with PD >= 4 mm showed the highest discrepancy between both groups (33% vs. 0%, p50% PD >= 4 mm) versus without (= 4 mm) generalized periodontitis had two different IL-1-haplotype patterns. Conclusions: The results confirm the association between AMI and periodontitis. A.a. and P.g. might be risk indicators for AMI. Two different IL-1 haplotypes may explain previous discrepancies in the association between cardiovascular diseases and periodontitis. Keywords: periodontitis, myocardial infarction, interleukin-1