Abstract: Objective: To investigate the relationship between increased peripheral blood platelets and rheumatoid arthritis(RA).Methods: One hundred and thirty-nine patients with RA were divided into normal platelet group and high platelet group according to the platelet count,and the difference between the clinical manifestation and laboratory examination was compared.At the same time,correlated analysis was carried out between the platelet count and the laboratory examination.Results: There was significant difference in swollen joint count,tender joint count,average erythrocyte sedimentation rate(ESR),C-reactive protein(CRP) and rheumatoid factor(RF) titer between the two groups(P<0.01).The platelet count of RA patients was positively correlated with ESR,CRP and RF titer(r=0.41,0.24,0.17,respectively,P<0.05 to P<0.01).The average level of anti-cyclic citrullinated peptide(CCP) antibody in the RA patients with platelet count over 450×10⁹/L was(199±96) u/ml,while the average level of anti-CCP in the other RA patients was(118±108) u/ml.The former was significantly higher(P<0.01);X-ray Ⅱ joints lesion was observed in more than 46.2% of the patients with platelet count over 450×10⁹/L RA,while it was 19.6% in the other group.The difference was not significant(P>0.05).Conclusions: Increased peripheral blood platelet count has some correlation with the activity of RA disease.Platelet count can be used as a simple and effective index to evaluate the activity of RA disease.