Background:Poststreptococcal reactive arthritis (PSRA) is a very common diagnosis in rheumatology practice, which develops after recent pharyngeal streptococcal infection and characterized by aseptic inflammation in one or more joints and periarticular involvement. Now no diagnostic criteria have been agreed [2,4]; association of the expression of HLA-B27 and PSRA is not clear [1,3].Objectives:In our study we analyzed the features of PSRA in presence of HLA-B27.Methods:88 patients (48 female and 40 male) aged between 18-55 years with complains of pain, tender and swollen joints developed after recent pharyngeal streptococcal infection underwent standard physical and laboratory rheumatological examinations. Acute rheumatic fever and other inflammatory arthritis were excluded.Results:60 patients (68,2%) had oligo-polyarthralgia, 10 patients (11,4%) - monoarthritis, 24 patients (27,3%) had asymmetrical olygoarthritis, 4 patients (4,5%) had polyarthritis, enthesitis was found in 4 (4,5%) patients, tenosynovitis of the palmar flexor tendons in 10 cases (11,4%) and the peroneal tendons of the ankles in 5 patients (5,7%), one-sided sacroiliitis (confirmed by MRI) in 5 patients (5,7%).The mean level of ASL-O was 542 U/ml, CRP -15 mg/L, ESR - 34 mm/H; HLA-B27 was present in 24 (30,7%) patients. HLA-B27 positivity was connected to enthesitis, sacroiliitis, more joint involvement with higher levels of ESR and CRP.Conclusion:30% of patients with poststreptococcal reactive arthritis are HLA-B27 positive, the presence of HLA-B27 leads to more frequent development of enthesitis, polyarthritis and sacroiliitis with higher level of inflammatory activity which dictate the need for longer supervision of such patients for possible triggering of ankylosing spondylitis development.References:[1]Ahmed S, Ayoub EM, ScorniK JC, Wang C-Y, She J-X. Poststreptococcal reactive arthritis. Clinical characteristics and association with YLA-DR alleles. Arthritis Rheum 1998; 41:1096-102.9[[2]Gibofsky A, Khanna A, Suh E, et al. The genetics of rheumatic fever: Relationship to streptococcal infection and autoimmune disease. J Rheumatol Suppl. 1991;30:1–5. [PubMed] [Google Scholar][3]Leitch DN, Holland CD/ Reactive arthritis, beta-hemolytic Streptococcus and Staphylococcus aureus. Br J Rheumatol 1996;35:912.[4]Mackie SL, Keat A. Poststreptococcal reactive arthritis: what is it and how do we know? Rheumatology (Oxford) 2004;43:949–54. 10.1093/rheumatology/keh225 [PubMed].Disclosure of Interests:None declared