The synaptosomal-associated protein (SNAP-25) plays an integral role in synaptic transmission and in memory consolidation in the hippocampus. Recently an association between SNAP-25 gene polymorphism and cognitive ability has been reported in two independent studies of healthy people and patients with schizophrenia. Authors carried out an association study of MnlI SNAP-25 polymorphism and performance on neurocognitive tests measuring verbal memory, attention/executive functions in 66 patients with major psychosis, 75 their relatives and 136 controls. MANCOVA revealed a significant effect of group (small er, Cyrillic=0,00001) and genotype (small er, Cyrillic=0,012) as well as an interaction effect between group and genotype (small er, Cyrillic=0,02) on the performance on neurocognitive tests. Carriers of the TT genotype performed worse on the most tasks compared to other genotypes. The similar character of the MnlI SNAP-25 polymorphism effect on the variability of neurocognitive traits in all groups suggests the relationship between this gene and general cognitive ability.