In the United States, adolescents who are lesbian, gay, or bisexual (LGB) face disparities across physical and mental health outcomes compared with non-LGB youth, yet few studies have looked at patterns of health care utilization by sexual orientation. To compare health care utilization indicators for LGB and non-LGB youth. This cohort study analyzed wave 3 data from Healthy Passages, a longitudinal observational study of diverse public school students in Birmingham, Alabama; Houston, Texas; and Los Angeles County, California. Multivariable logistic regression models tested sexual-orientation differences in the past 12-month health care utilization measures, controlling for youth age, gender, race and ethnicity, household education, income, and marital status. Data collection began in 2010 when students were in the 5th grade (mean [SE] age, 11.13 [0.01] years) (wave 1) and continued 2 years later (wave 2, 7th grade) and 5 years later (wave 3, 10th grade). Permission to be contacted was provided for 6663 children, and 5147 (77%) participated in audio computer-assisted self-administered interviews. This study included 4256 youth (640 LGB, 3616 non-LGB) who completed interviews at wave 1 and wave 3 and answered key items used in this analysis. Analyses were completed in June 2021. Sexual orientation (LGB vs non-LGB). Health care utilization and communication difficulty with a physician in the past 12 months. Among 4256 youths included in the study at baseline in 5th grade (wave 1), 2171 (48.9%) were female; 1502 (44.5%) were Hispanic or Latino; 1479 (28.9%) were Black; the mean (SE) age was 11.19 (0.03) years; and 640 (14.5%) were LGB at wave 3. Compared with non-LGB youth, a higher proportion of LGB youth reported not receiving needed medical care in the last 12 months (adjusted odds ratio [aOR], 1.68; 95% CI,1.38-2.05), most commonly for sexually transmitted infections, contraception, and substance use. LGB youth more frequently reported difficulty communicating with their physician (aOR, 1.71; 95% CI, 1.27-2.30) than non-LGB youth. This study's results found that health care utilization differs by sexual orientation for youth. These findings suggest that clinician training is needed to address the health care needs of LGB youth. Routinely capturing sexual orientation data might enable tracking of health care utilization indicators for LGB youth.