Medicated and unmedicated schizophrenic patients (both n's = 14) were compared to a normal control sample (n = 15) on two attentional tasks hypothesized to be markers of vulnerability to schizophrenia. These tasks, the continuous performance test and the visual backward masking task, were found to be more deviant in schizophrenic patients than in normals. In addition, the group mean levels of performance did not differ consistently across medication status within the medicated patients. It was found, however, that the association between these tasks varied as a function of medication status, with unmedicated patients more similar to normals than to medicated patients. The implications of these results for the two tasks as markers are discussed, with special focus on those earlier studies that did not evaluate unmedicated patients.