Bipolar disorder has been associated with dysfunction of executive control processes. Using functional magnetic resonance imaging, we examined brain activation during a counting Stroop task in 11 healthy adults and 11 patients with bipolar I disorder. Results revealed greater activation for the healthy than bipolar disorder group in distributed brain regions that included the right inferior and medial frontal gyri. With the exception of one area within the left posterior cingulate gyrus that was correlated with mania severity, regional activations where group differences were observed were not associated with mood symptoms in the patient group. These findings add to the growing body of evidence implicating neural circuitry subserving executive control in bipolar disorder.