OBJECTIVES: Post-menopausal women are under-diagnosed in claims data even though they exhibit symptoms. Probabilistic linkage was conducted between claims data and The University of Michigan Women’s Registry data to control for post-menopausal symptoms as risk factors in the analysis. METHODS: Women with a menopause diagnosis who used estrogen only hormone therapy (HT) were selected from the registry data. A separate group of patients age 45 or older who were prescribed estrogen only HT was selected from a large U.S. claims database. Logistic regression was conducted to calculate the propensity score for each patient, controlling for women’s health-related comorbidities in each population. Patients with the closest propensity score from each group were matched, and the menopause symptoms of Registry patients were added to the claims records of the corresponding matched patients in the claims data. This linkage process was repeated 250 times, and the mean and 95% confidence interval (CI) of healthcare costs during the follow-up period were calculated. RESULTS: Among 2771 women, 16% (N=443) were diagnosed as post-menopausal. Of this subset, 83 patients prescribed estrogen only HT were selected. After probabilistic linking with the 20,020 selected women from the claims database, 80 patients from each population were matched. The average cost of patients with at least one symptom was much higher compared to patients without symptoms ($13,570 [95% CI: $13,459-$13,680] vs. $3,391 [95% CI: $3,345-$3,436], p-value<0.001). Cost differences were mainly from inpatient ($1,997 [95% CI: $1,925-$2,070], p-value<0.001 vs. $247 [95% CI: $239-$254, p-value<0.001), physician visit ($967 [95% CI: $961-$974], p-value<0.001 vs. $248 [95% CI: $246- $251], p-value<0.001), and pharmacy costs ($3,676 [95% CI: $3,648-$3,704], p-value<0.001 vs. $903 [95% CI: $890- $916], p-value<0.001). CONCLUSIONS: The study suggests that post-menopausal symptoms are important risk factors to control when assessing health care costs in claims data. Probabilistic linkage can bridge the gap between claims and registry data information.