Objective: The main aim of the study was to examine blood oxygen level-dependent response during task switching in adults with attention-deficit/hyperactivity disorder (ADHD). Method: Fifteen male adults with ADHD and 14 controls participated and performed a task-switching paradigm. Results: Behaviorally, no specific executive control problems were observed in the ADHD participants, although they did display more errors in general. The neuroimaging data did show remarkable differences between the ADHD and control adults: Adults with ADHD engaged more strongly the dorsal anterior cingulate cortex, middle temporal gyrus, precuneus, lingual gyrus, precentral gyrus, and insula than did the healthy controls during task switching. Controls displayed more task-related activity in the putamen, posterior cingulate gyrus, medial frontal gyrus, thalamus, orbitofrontal cortex, and postcentral gyrus. Conclusions: ADHD adults did not display specific executive control problems at a behavioral level, but did engage different brain areas during task switching compared with healthy controls. The results are discussed in the framework of the executive frontostriatal circuitry, conflict detection, and attentional networks. © 2010 American Psychological Association.