We studied the relationship between DRD5 gene polymorphism presented by microsatellites with cognitive signs in 152 schizophrenic patients, 81 mentally healthy relatives, and 125 mentally healthy control individuals. An association was found between DRD5 polymorphism with efficiency of visual voluntary attention in patients (p = 0.02) and their relatives (p = 0.006). Carriers of two copies of the 148-b.p. allele were characterized by low efficiency of attention.