OBJECTIVE: To characterise Achilles tendon structure and thickness a minimum of 8 years after intra-tendinous surgery. Material and METHODS: Fourteen patients (16 tendons; 9 men and 5 women, mean age 43 years, range 27-55) surgically treated (intra-tendinous surgery) for chronic painful midportion Achilles tendinosis, were followed with clinical examination and grey-scale ultrasonography for a minimum of 8 years (range 8-16 years, mean 13 years). RESULTS: All patients were satisfied with the result of surgery and were active in Achilles tendon loading activities without restrictions. In all operated tendons, structural abnormalities remained and tendons remained thicker than normal tendons. CONCLUSIONS: Resection of tendinosis is associated with persistent structural abnormalities and thickening of the tendon 13 years after surgery, despite successful clinical outcomes.