Objective: To complete an exploratory uncontrolled study of the effects of lisdexamfetamine dimesylate (LDX) on growth of children treated for attention-deficit/hyperactivity disorder (ADHD). Method: Height, weight, and body mass index (BMI) from 281 children ages 6 to 13 years from longitudinal assessments up to 15 months were compared to norms from the Centers for Disease Control. Results: At study entry, children were taller and heavier than average. Growth delays were largest for weight and BMI, and there was a 13 percentile point decrease in height. Children continued to grow in terms of height while treated with LDX; we found no increase in raw weight or BMI during the study period. LDX treatment was significantly associated with diminished gains in height, weight, and BMI compared to levels that would be expected based on age-appropriate standards from the Centers for Disease Control. Growth delays were greatest for the heaviest and tallest children, for those who had not previously received stimulant therapy, and for those with a greater cumulative exposure to LDX. More work is needed to determine effects on ultimate adult height. Conclusions: Consistent with prior studies of stimulants, treatment with LDX leads to statistically significant reductions in expected height, weight, and BMI. Growth of patients with ADHD treated with LDX should be closely monitored and corrective action taken should growth delays be observed. (Contains 5 tables and 2 figures.)