Background: Representing the pathological extreme pursuit of muscularity, muscle dysmorphia (MD) is characterized by a pervasive belief or fear around insufficient muscularity and an elevated drive for muscularity. Despite evidence of elevated body image-related concerns among sexual minority populations, little is known about the degree of muscle dysmorphia (MD) symptoms among sexual minorities, particularly based on Muscle Dysmorphic Disorder Inventory (MDDI) scores. The objective of this study was to examine the nature and severity of MD symptoms in cisgender sexual minority men and women and provide community norms of the MDDI for these populations. Methods: Data from participants in The PRIDE Study, an existing study of health outcomes in sexual and gender minority people from the United States, were examined. Participants included cisgender gay men (N = 1090), cisgender bisexual plus (bisexual, pansexual, and/or polysexual) men (N = 100), cisgender lesbian women (N = 563), and cisgender bisexual plus women (N = 507). We calculated means, standard deviations (SD), and percentiles for the MDDI total and subscale scores for cisgender sexual minority men and women. We compared MDDI scores by sexual orientation using linear regression models, both unadjusted and adjusted for sociodemographics. Results: Overall, the sample was 85.2% White, 3.0% Asian or Pacific Islander, 2.0% Black, 0.5% Native American, 3.9% multiracial, and 6.6% Hispanic/Latino/a. The mean age was 38.6 (SD = 14.3) and 69.4% had a college degree or higher. Means (SD) for the MDDI total score were 27.4 (7.7) for cisgender gay men, 26.4 (6.4) for cisgender bisexual plus men, 24.3 (6.1) for cisgender lesbian women, and 24.6 (5.5) for cisgender bisexual plus women. There were no significant differences in MDDI scores between cisgender gay and bisexual plus men, or between cisgender lesbian women and bisexual plus women in unadjusted or adjusted models. Conclusions: These normative data provide insights into the experience of MD symptoms among cisgender sexual minority men and women and can aid researchers and clinicians in the evaluation of MD symptoms and interpretation of MDDI scores in sexual minority populations.