Different aspects of attention, e.g. phasic alertness, vigilance, divided attention, response flexibility, response inhibition and intermodal integration, were investigated with a computerized test-battery in a group of 20 patients with Huntington's disease and 27 healthy controls. Huntington's disease patients are not impaired in reacting to task-contingent external stimulation in the phasic alertness task, but the self-generated maintenance of attention as measured by the vigilance task, is disturbed. The simultaneous monitoring of different input-channels in the divided attention task and the ability to operate with information given to different modalities in the intermodal integration task are severely affected. The performance of Huntington's disease patients in the response flexibility task, in which internal cued shifts are required, is impaired. Huntington's disease patients are also impaired in reacting selectively to go/no-go stimuli in the response inhibition task. It is suggested that a number of ‘higher’ cognitive deficits described in Huntington's disease might, at least partly, be due to basic attentional disturbances.