Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease affecting children aged less than 16 years, characterized by chronic synovitis, cartilage damage, and bony erosions mediated by matrix metalloproteinases (MMPs), mainly MMP- 1 and MMP-3. The purpose of this study was to investigate MMP-1 and MMP-3 gene polymorphisms in patients with JIA, the role of genes in susceptibility to JIA, and their associations with JIA activity and prognosis. Case–control study included 100 patients diagnosed with JIA, according to the criteria of the International League of Associations for Rheumatology (ILAR), and 100 healthy children, age and sex matched, as controls. The MMP-1 (21607 1G/2G) and MMP-3 (21171 5A/6A) polymorphisms were screened by polymerase chain reactionrestriction fragment length polymorphism. The serum levels of MMP-1 and MMP 3 were measured by enzyme-linked immunosorbent assay. There were significant differences between patients with JIA and control groups regarding the genotype and allele frequencies distributions of both MMP-1 1G/2G and MMP-3 5A/6A polymorphisms. The haplotype 2G-6A, which carries the abnormal alleles, showed higher frequencies in patients with JIA than in controls (OD= 2.8, P =0.002). The prevalence of MMP-1 2G and 6A allele for MMP-3 polymorphism was found to be significantly associated with persistent oligoarticular, rheumatoid factor (RF)-positive polyarthritis, and systemic JIA groups. There were significantly increased serum levels of MMP-1 and MMP-3 associated with 2G/6A haplotype in the patient group, especially with the polyarticular RF (1ve) group than in other groups and the control group. MMP-1 and MMP-3 haplotypes could be useful genetic markers for JIA susceptibility and severity in the juvenile Egyptian population. Moreover, our data further support the use of serum MMP-3 and MMP-1 as specific markers of disease activity in JIA.