Objective: To assess the short-and long-term cardiovascular effects of once-daily treatment with a mixed amphetamine salts extended-release formulation (MAS XR; Adderall XR ) in children age 6 to 12 years with attention-deficit/hyperactivity disorder (ADHD). Study design: Short-term cardiovascular effects were assessed during a 4-week, double-blind, randomized, placebo-contr-olled, forced-dose-titration study of once-daily 10, 20, and 30 mg MAS XR (n=580). Long-term cardiovascular effects were assessed in 568 subjects during a 2-year, open-label extension study of MAS XR (10 to 30 mg/day) . Resting sitting blood pressure and pulse were measured at baseline and weekly during the short-term study, then monthly during long-term treatment. Results: Changes in blood pressure, pulse, and QT interval corrected by Bazett’ s formula (QTcB) in children receiving MAS XR were not statistically significantly different than those changes seen in children receiving placebo during short-term treatment. Mean increases in blood pressure after 2 years of MAS XR treatment (systolic, 3.5 mm Hg; diastolic, 2.6 mm Hg) and pulse (3.4 bpm) were clinically insignificant, and there was no apparent dose-response relationship. Conclusions: Cardiovascular effects of short-and long-term MAS XR were minimal during short-and long-term MAS XR treatment at doses of ≤ 30 mg/day in otherwise healthy children. Objective: To assess the short-and long-term cardiovascular effects of once-daily treatment with a mixed amphetamine salts extended-release formulation (MAS XR; Adderall XR) in children age 6 to 12 years with attention-deficit / hyperactivity disorder ADHD. Study design: Short-term cardiovascular effects were evaluated during a 4-week, double-blind, randomized, placebo-contr olled, forced-dose-titration study of once-daily 10, 20, and 30 mg MAS XR (n = 580). Long-term cardiovascular effects were assessed in 568 subjects during a 2-year, open-label extension study of MAS XR (10 to 30 mg / day). Resting sitting blood pressure and pulse were measured at baseline and Weeks in the short-term study, then monthly during long-term treatment. Results: Changes in blood pressure, pulse, and QT interval corrected by Bazett’s formula (QTcB) in children receiving MAS XR were not statistically significant different than those changes seen in children receiving placebo during short-term treatm ent. Mean increases in blood pressure after 2 years of MAS XR treatment (systolic, 3.5 mm Hg; diastolic, 2.6 mm Hg) and pulse (3.4 bpm) were clinically insignificant, and there was no apparent dose-response relationship. effects of short-and long-term MAS XR were minimal during short-and long-term MAS XR treatment at doses of ≤ 30 mg / day in otherwise healthy children.