OBJECTIVE: To assess the effects of intratendinous injection of 12.5% dextrose water on healing of injured Achilles tendon in rat. METHOD: Quantification of hydroxyproline concentration in Achilles tendons of 21 Sprague-Dawley rats was performed to assess the concentration of collagen, and hematoxyline-eosin and immunochemistry staining was performed to analyse histopathology. RESULTS: There was no significant difference in collagen concentration between the three groups (p>0.05). Light microscopic examination showed irregular arrangement of coarse collagen fibers and decreased number of fibroblasts in sham treatment and dextrose injection group and showed more irregular arrangement of coarse collagen fibers in dextrose injection group than in sham treatment group. The immunochemical staining of sham treatment and dextrose injection group showed more increased immunoreactivity for type I and III collagen than control group, but the same as in sham treatment group and dextrose injection group. CONCLUSION: The increase of collagen concentration in injured Achilles tendon of rat treated with hyperosmolar dextrose was not found. This implies that clinical observation of collagen remodelling process may alter biomechanical property other than collagen concentration which should be further investigated.