Purpose To evaluate the diagnostic value of high-frequency ultrasonography (HFUS) in the diagnosis of rheumatoid arthritis (RA) Achilles tendinopathy.Materials and Methods The Achilles tendon HFUS findings in 67 cases including a total of 93 feet were analyzed retrospectively,among which,11 cases including 22 feet were set as healthy control group (group A),36 cases including 40 feet as RA Achilles tendon group (group B) and 20 cases including 31 feet as non RA Achilles tendon group (group C).HFUS was used to observe the gray-scale imaging (GSI) and power Doppler imaging (PDI) features of the Achilles tendon:① the positive rate of Achilles tendon GSI abnormality.② The thickness and width of the starting point,mid point and ending point of Achilles tendon.③ The detection rate of retrocalcaneal bursal effusion.④ The detection rate of blood flow signal in the internal Achilles tendon.⑤ The level of blood flow signal.The data of each group were compared and analyzed.Restlts ① The positive rate of Achilles tendon GSI abnormality:there was no significant difference between group A and group B (x2=0.064,P＞0.05).Compared with group A and group B,group C had higher rate of abnormalities (x2=31.601 and 39.256,P＜0.05).② The thickness and width of Achilles tendon:the thickness of each point increased in group C than that in group A and group B (P＜0.05),and there was no significant difference in width between groups (P＞0.05).③ The detection rate of retrocalcaneal bursal effusion:negative in group A.The detection rate of group B (55％) was higher than that of group C (19.4％),the difference was statistically significant (P＜0.05).④ The detection rate of blood flow signal in the Achilles tendon:negative in group A.The detection rate of group B (97.5％) was higher than that of group C (45.2％),the difference was statistically significant (P＜0.05).⑤ The level of blood flow signal:level Ⅰ signal detection rate in group B (7.5％) was lower than that in group C (35.5％),while level Ⅱ signal detection rate in group B (35.0％) was higher than that of group C (9.7％),the differences were statistically significant (P＜0.05).Level Ⅲ signal was detected in only group B (45.0％) while not detected in group C.In addition,aspiration biopsy was performed on 3 patients of whom the fat pad of Achilles tendon was involved by level Ⅲ blood flow signal in PDI,and the pathological findings were consistent with ultrasonic manifestations.Conclusion HFUS is of great value in the diagnosis of RA Achilles tendinopathy and it can also be used to distinguish from non-RA Achilles tendinopathy.Moreover,it helps to achieve early diagnosis and early treatment in clinic to avoid Achilles tendon rupture and other bad progresses.