ACL injury has been associated with a decrease in proprioceptive performance and specifically postural control. Tests of postural control have been criticised for not being sufficiently challenging. The Star Excursion Balance Test (SEBT) has been proposed to offer sufficient challenge to be a sensitive test for detecting performance deficits related to pathology. The purpose of this study was to determine if decrements SEBT reach distance is associated with ACL deficiency (ACLD). Twenty five ACLD patients ACLD (17 male and 8 female, mean age 30 (SD 4.5) years) and twenty five matched controls were examined carrying out the SEBT. Factorial ANOVA showed the main effects of limb (p=0.006) and direction (p<0.001) and interaction of limb and direction (p=0.015) all had significant differences between the groups. Further analysis revealed significant differences between the control group and the ACLD limb for the limb movement directions of anterior (p=0.0032), lateral (p=0.005), posterior-medial (p=0.0024) and medial (p=0.001). There were also significant differences between the control limbs and uninjured limb of the patients for the directions of medial (p=0.001) and lateral (p=0.001). ACLD patients appear to have deficiencies in their dynamic postural control when compared to normal asymptomatic subjects. Interestingly, in the ACLD patients, their uninjured leg show deficits compared to the control in two of the four directions the ACLD leg was deficient, this may be indicative of a postural control deficit in these patients, which may have predisposed to the ACL injury and would warrant further study.