The Midlife Women’s Symptom Index (MSI) was designed to measure menopausal symptoms specifically in a multiethnic sample of midlife women. This study is a psychometric property test to evaluate MSI among 512 multiethnic groups of midlife women (White, Hispanic, African American, and Asian American). Across the ethnic groups, MSI had an adequate internal consistency in all subdomains except psychosomatic symptoms. The item-to-total correlation coefficients of “lost weight” and “nosebleeds” were less than 0.20 among all ethnic groups. The discriminant validity was confirmed among all ethnic groups except Asian Americans. Overall, MSI may work better for Whites and not as well for Asian Americans, compared with other ethnic groups. Additional studies with diverse groups of multiethnic midlife women are needed, however, to confirm MSI psychometric properties.