OBJECTIVE: To describe changes in blood pressure (BP) and body mass index (BMI) associated with stimulant medication fills in children. METHODS: Observational, retrospective matched cohort study of children 6-17.9 years initiating stimulant medication between 7/1/2010-6/30/2017 matched 1:3 by age, race, ethnicity, and sex to children with no stimulant use during this period. All BPs and BMIs recorded during ambulatory visits were identified. Generalized linear models were used to estimate differences in change in systolic BP (SBP), diastolic BP (DBP), and BMI over time. RESULTS: The 686 children with stimulant prescription fills and 2048 matched controls did not differ by baseline SBP or BMI. The matched control group (30.5% female, mean age 11.2 ± 3.4 years 79.7% white) was more likely to be publicly insured (35% vs. 21%, P < .01). After adjusting for baseline values, over a mean follow-up of 144 days change in SBP or DBP did not differ significantly between patients with stimulant medication fills and matched controls. Stimulant use was associated with a 4.7 percentile decrease in BMI percentile compared to matched controls (95% CI: 3.69, 5.71; P < .01). CONCLUSIONS: In a pediatric primary care cohort, stimulant prescription fills were associated with marked decreases in BMI but no significant changes in BP over time.