Background In the last decades the interest in the problems of poststreptococcal reactive arthritis/PSReA/growed up caused by the increased number of publications on it.

Objectives The aim of the work is to make comparison between acute rheumatic fever/ARF/and PSReA from the clinical and laboratory aspects.

Methods Object of the investigation were 9 men aged 19,0 ± 1,0/18–21/fulfiled Jones criteria/1992/for ARF and 8 men and 2 woman aged 21,5 ± 5,6/18–32/fulfiling criteria of the Canadian Paediatric Society/1995/for PSReA. The patients were investigated and treated clinically and followed up till 60–90 th day.

Results ARF developed more often after tonsillitis, PSreA – after catarrh of upper respiratory ways, the latent period being longer in ARF/20 ± 4,5 days/than in PSReA/11,8 ± 16,7 days/. The acute onset and fever were more characteristic of ARF than of PSReA. In ARF joint index was higher, joints were migratorily affected, the pain at rest was more violent, the leucocytes, ESR, AST-O and anti-DN-ase B showed higher values. In PSReA the joint affection was cumulative, the enthezopathies – more frequent and some morning stiffness existed. Auscultative finding and ECG changes were established only in ARF. After treatment beginning the joint syndrome in ARF was over in few days whereas in PSReA it persisted within a month. Normalisation of the laboratory changes occurred more slowly again in PSReA.

Conclusion Despite of the same aetiology/antecedent streptococcal infection/the established clinical and laboratory features of ARF and PSReA permit to consider them as separate nosological units.