There has been little investigation of the attentional processes associated with multiple personality disorder (MPD). Divided attention performance in the copresent condition (i.e., two personalities simultaneously attending to the environment) was studied in a subject diagnosed with MPD. As predicted, recall of both visually presented digits and auditory consonants was enhanced in the copresent condition and was significantly better than the same divided attention performance when only one personality participated. A comparison with a normal reference group suggested the MPD subject performed similar to the normal group in both single-task performance and divided attention performance in the copresent condition. However, performance of the MPD subject appeared attenuated when only one alter attended to the tasks. A possible increase in brain activation during the copresent condition may explain these findings. Further research of attentional processes associated with MPD and other dissociative disorders is indicated.