Muscle dysmorphia (MD) is characterized by extreme preoccupation with insufficient muscularity that prompts pathological behaviors and distress/impairment. The Muscle Dysmorphic Disorder Inventory (MDDI) - a widely used measure of MD symptoms - has yet to be validated among transgender women, despite emerging evidence suggesting risk for muscularity-oriented concerns in this population. We examined the MDDI factor structure as well as the reliability and validity of its subscales in a sample of 181 transgender women ages 19-73 years who participated in a national longitudinal cohort study of U.S. sexual and gender minority adults. Confirmatory factor analysis was used to examine model fit for the original three-factor structure of the MDDI (drive for size, appearance intolerance, functional impairment). A re-specified three-factor model allowing covariance of residuals for two conceptually related items demonstrated good overall fit (χ/df = 1.33, CFI =.94, TLI =.93, RMSEA =.06 [95 % CI =.01,.09], SRMR =.07). Moreover, results supported the internal consistency and convergent and discriminant validity of the MDDI subscales in transgender women. Findings inform the use of the MDDI among transgender women and provide a foundation to support future research on the MDDI and MD symptoms among gender minority populations.