The role of anthropometric measurements in the prediction of hamstring autograft size remains unclear. In this internal review board–approved study, we evaluated medical records for patients receiving anterior cruciate ligament (ACL) reconstruction with hamstring autograft at our institution between 2006 and 2008. One hundred and thirty-two patients received hamstring autografts. Correlation coefficients and step-wise multiple linear regression analysis were used to determine the relationships between sex, age, height, body mass index (BMI), and hamstring graft diameter. Women had significantly smaller grafts than men (P<.00001). Twenty-four patients had grafts less than 7 mm in diameter and 18 of those patients were female. Age and BMI did not correlate with graft diameter in women. Height correlated to graft diameter in women (P = .002, R2 = 0.14). Women shorter than 65 in had significantly smaller graft diameters (mean [SD], 6.94 [0.45] mm), than those women 65 in and taller (mean [SD], 7.20 [0.49] mm; (P = .03). Age and height did not correlate with graft size in men. BMI greater than 25 kg/m2 correlated with larger graft diameter, but BMI less than 18 kg/m2 did not predict graft sizes less than 7 mm. Therefore, alternative graft options should be considered in women less than 65 in tall.