The efficacy and safety of lisdexamfetamine dimesylate (LDX) vs placebo in binge eating disorder (BED) was evaluated in two multicenter, double-blind, placebo-controlled trials. Adults (study 1, n=383; study 2, n=390) meeting DSM-IV-TR BED criteria were randomized (1:1) to placebo or LDX (50 or 70 mg/day) dose titration; optimized doses were maintained to the end of double-blind treatment (week 12/early termination). Change from baseline in binge eating days/week at weeks 11-12 (primary efficacy endpoint) was assessed with mixed-effects models for repeated measures. Secondary endpoints related to binge eating and medical parameters, safety, and treatment compliance were also assessed. Least squares mean (95% CI) treatment differences for change from baseline binge eating days/week at weeks 11-12 significantly favored LDX (study 1: -1.35 [-1.70, -1.01]; study 2: -1.66 [-2.04, -1.28]; both P<0.001). In both studies, treatment-emergent adverse events (TEAEs) reported by ⩾10% of LDX participants were dry mouth, insomnia, and headache. Serious TEAEs occurred in two (1.1%) placebo participants in each study and in three (1.6%) and one (0.6%) LDX participants in study 1 and study 2, respectively. Across studies, mean increases from baseline at week 12/early termination with LDX for pulse and systolic and diastolic blood pressure ranged from 4.41-6.31 b.p.m. and 0.2-1.45 and 1.06-1.83 mm Hg, respectively. LDX (50 and 70 mg/day) was superior to placebo in decreasing binge eating days/week from baseline and improving binge eating-related key secondary endpoints. Safety results appear consistent with the known safety profile of LDX.