This study evaluated the efficacy and tolerability of lisdexamfetamine (LDX) in the treatment of bipolar depression. Twenty-five outpatients with bipolar I or II disorder and syndromal depression despite at least 4 weeks of stable mood stabilizer and/or antipsychotic therapy were randomized to receive LDX (N=11) or placebo (N=14) in an 8-week, prospective, parallel-group, double-blind study. In the primary longitudinal analysis, LDX and placebo produced similar rates of improvement in depressive symptoms as assessed by the Montgomery–Asberg Depression Scale. However, LDX was associated with a statistically significantly greater rate of improvement in self-reported depressive symptoms and daytime sleepiness, and with greater reductions in fasting levels of low-density lipoprotein and total cholesterol. In the secondary baseline-to-endpoint analysis, LDX was associated with statistically significant improvements in self-reported measures of depression, daytime sleepiness, fatigue, and binge eating, as well as with improvements in fasting levels of triglycerides and low-density lipoprotein and total cholesterol. LDX was well tolerated and was not associated with any serious adverse events, but there was one case of suspected misuse. The small sample size (because of premature study termination by the funding sponsor) may have limited the detection of important drug–placebo differences. Larger studies on the use of psychostimulants for treatment of bipolar depression seem warranted.