Abstract: Objective: While age has been recognized as a noteworthy factor in preoperative graft selection, the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientific community. This study aimed to explore the correlation between the diameter of autologous tendon grafts and age in anterior cruciate ligament reconstruction (ACLR). Methods: A retrospective review of 388 patients who underwent arthroscopic ACLR with hamstring autografts was performed. Patients were grouped by age to analyze differences in hamstring autograft diameter and tendon cross-sectional area (CSA). We explored the correlations between age and graft diameter and between age and the CSA of the popliteal tendon while controlling for the influence of other pertinent variables. Results: Compared with female patients, male patients presented significantly greater autograft diameters and hamstring tendon CSAs (P<0.05). Notably, graft diameter and hamstring tendon CSA varied significantly across different age groups (P<0.05); patients aged >32 years were substantially more likely to have a graft diameter exceeding 8 mm and a CSA surpassing 18.5 mm² than their ≤32-year-old counterparts were (P<0.05). Conclusion: This study revealed that graft diameter varies across different age groups, with age independently influencing graft diameter.