Fifty HIV-infected individuals and 20 uninfected controls participated in an investigation of dual task performance in HIV-1 infection. Participants first engaged in a simple auditory reaction time (RT) task followed by a visual choice RT task (single task condition), and then they simultaneously engaged in both tasks (dual task condition). Under single task conditions, the HIV+ participants did not significantly differ from controls on either simple or choice RT (though a trend was evident on single task choice RT). In contrast, under dual task conditions the HIV+ group's performance decrement, relative to controls, was significantly greater on both simple and choice RT. This dual task decrement was also significantly associated with slower performance on the interference condition of the Stroop. Patients with AIDS tended to have greater dual task decrements than did the pre-AIDS group, though this fell short of statistical significance. These results suggest that HIV-1 infection leads to deficits in divided attention and the simultaneous processing of competing stimuli, deficits which have been linked to disruption of the anterior attentional system.