For many years, tendinopathies were considered to be mainly degenerative. However, recent research indicates that chronic inflammation may be a feature of Achilles tendinopathy. Thus, the aim of this study was to investigate, if plasma levels of the inflammatory cytokine interleukin‐6 (IL‐6) are elevated in patients with chronic Achilles tendinopathy and if IL‐6 levels are affected by physiotherapeutic treatment, duration of symptoms or anatomical localization. Male patients with chronic insertional (n = 16) or mid‐portion (n = 15) Achilles tendinopathy were subjected to a physiotherapeutic intervention for 12 weeks. VISA‐A scores and blood plasma IL‐6 levels were determined before and after the intervention. From pre to post, VISA‐A scores (57 ± 13 to 74 ± 18 points) increased while mean plasma IL‐6 levels decreased significantly (2.5 ± 1.6 to 1.9 ± 0.7 ng/L). Patients with insertional did not significantly differ from patients with mid‐portion Achilles tendinopathy. Of all investigated parameters, pre‐ and post‐IL‐6 levels correlated weakly with age only (r = 0.388 and r = 0.389). In a subgroup of patients, inflammation appears to play a role in the context of Achilles tendinopathies, making IL‐6 a potential target for therapeutic interventions in this subgroup. Common factors leading to elevated IL‐6 levels need to be identified in future studies.