Combining the Continuous Performance Test (CPT) with a modern functional imaging technique provides a powerful tool for investigating neurophysiological processes in the human brain. There is increasing evidence from single photon emission tomography (SPECT), positron emission tomography (PET) and presently also functional magnetic resonance imaging (fMRI) studies proposing the existence of a distributed large-scale attentional network, mediated by the dorsolateral prefrontal and mesial frontal cortex, thalamus, basal ganglia and posterior parietal and superior temporal lobe. The aim of this study is to show that fMRI is a useful tool for in vivo localization of attentional tasks and to compare the results with established imaging techniques. Functional MRI was performed on a clinical 1.5-T system using gradient-echo acquisition. For data processing, the Statistical Parametric Mapping (SPM96) package was used. A right lateralized activation pattern in the dorsolateral prefrontal and mesial frontal cortex, the thalamus and the basal ganglia was found in a group of 12 male subjects. These findings support theories suggesting right hemispheric dominance of human attention.