© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.Background and objective: The plasminogen (PLG) activation system plays an essential role in severe inflammation based diseases such as periodontitis, destructive membranous periodontal disease (ligneous periodontitis), familial Mediterranean fever (FMF), and amyloidosis. We have aimed to evaluate variations in PLG and the associations between PLG and MEFV genotypes in patients with FMF/ FMF-related secondary amyloidosis and periodontitis. Material and methods: A total of 247 individuals who were either diagnosed with FMF or systemically healthy were recruited to this human observational study with a cross-sectional design. All individuals were also diagnosed with periodontitis or periodontally healthy. Blood samples were obtained from patients with FMF and systemically healthy controls. Clinical periodontal indicators were recorded. All polymorphisms located in exons 6 and 8 of PLG and mutations located on exons 2 and 10 of the MEFV gene were analyzed by DNA Sanger Sequencing. Genotypes and allele frequencies of PLG and MEFV were detected and tested by the Hardy-Weinberg equilibrium. Serum levels of amyloid A (SAA), high-sensitive C-reactive protein (hs-CRP), PLG, and salivary PLG levels were determined by using enzyme-linked immunosorbent assay (ELISA). Results: Two polymorphisms were identified in PLG: G to A polymorphism on the 14th nucleotide of intron 8 and C to T polymorphism on the 924th nucleotide of the coding region (IVS 8+14 G>A and c.924C>T, respectively). In IVS 8+14 G>A polymorphisms, wild-type genotype: GG, heterozygote genotype: GA and homozygote genotype: AA. In c.924C>T polymorphism, wild-type genotype: CC, heterozygote genotype: CT and homozygote genotype: TT. The frequency of the heterozygous polymorphisms of PLG was significantly increased (17.6%) in FMF patients with periodontitis (p =.027). A large proportion of the test group that was heterozygous for MEFV-R202Q also had heterozygous PLG polymorphisms. Remarkable exacerbation in periodontal parameters was observed in patients with FMF and amyloidosis. SAA and hs-CRP levels were significantly correlated with salivary PLG levels in patients with periodontitis and heterozygous PLG. Conclusions: The current study describes IVS 8+14 G>A (rs2295368) and c.924C>T (rs1380916375) polymorphisms for the first time in the periodontal literature, which might play an important role in the pathogenesis of periodontitis, FMF, or amyloidosis. The elucidation of PLG polymorphisms is beneficial from a public health perspective by increasing the quality of life in these patients and reducing the mortality and morbidity associated with inflammatory diseases such as periodontal disease, FMF, and FMF-related amyloidosis.