This study evaluates changes in ACL T2* metrics over the course of the female menstrual cycle. In the pre-ovulatory phase, normally ovulating case subjects demonstrated significant shortening of T2*S and PS in comparison to visit #4 (post-ovulatory phase). Non-ovulatory control subjects displayed no significant changes over time. These findings suggest that shifts in collagen bound water occur within the ACL over the course of the menstrual cycle. Shifts in tissue water content have been associated with altered mechanical properties, and changes in ligament stiffness may alter proprioceptive sense, contribute to increases in laxity, and alter ACL-injury risk.