OBJECTIVE: Menorrhagia, or heavy menstrual bleeding (HMB), has a negative impact on women's quality of life (QOL). The objective was to develop, validate, and assess the performance of a disease-specific patient-reported outcome (PRO) measurement instrument for HMB (the Menorrhagia Impact Questionnaire [MIQ]). RESEARCH DESIGN AND METHODS: The MIQ was designed to measure the effect of HMB on a woman's self-assessment of menstrual blood loss (MBL), limitations in social/leisure activities, physical activities, and ability to work. Meaningfulness of these observed MBL changes were also measured. The development and psychometric validation of the MIQ was performed utilizing data from a long-term safety study of tranexamic acid (Lysteda * *Lysteda is a registered trade name of Ferring Pharmaceuticals Inc., Parsippany, NJ, USA. ), with comparison to an age-matched normal control group recruited from the general population. Performance of the MIQ was also evaluated using data from a six-cycle, randomized, double-blind, clinical study of tranexamic acid for the treatment of HMB. Correlations and sensitivity of each pertinent MIQ item to the treatment-induced changes in MBL were assessed, and the minimally important differences (MID) for the individual MIQ items were determined. RESULTS: The psychometric properties of the MIQ were fully validated. Correlations between individual MIQ items and changes in MBL were statistically significant (p < 0.001). A clear differentiation between tranexamic acid and placebo groups confirmed sensitivity of the MIQ and its ability to detect treatment-induced changes in MBL. MIDs were estimated for the individual MIQ items, with sensitivities and specificities in the 64-79% and 63-82% ranges using receiver operating characteristic (ROC) curve analyses, respectively. MIDs were found to be equal to or greater than 0.5. Statistically significant treatment differences were also observed for the proportions of subjects achieving at least 1-point improvement in MIQ scores. CONCLUSION: The MIQ contains validated constructs important to women with HMB. CLINICAL TRIAL REGISTRATION: NCT00113568 and NCT00386308 (ClinicalTrials.gov ID).