A subtle genetic defect in homocysteine metabolism is thought to play an etiologic role in schizophrenia. Cystathionine-beta-synthase (CBS) is a key enzyme related to homocysteine levels. The aim of the present study was to search for association between the 844ins68 polymorphism of the CBS gene and schizophrenia in a large Russian sample using case-control and family-based designs. The sample comprised 1135 patients, 626 controls and 172 families. There was a trend for association between the 844ins68 polymorphism and schizophrenia in the case-control study, with higher frequency of the insertion in the control group. The FBAT revealed a statistically significant difference in transmission of alleles from parents to the affected proband, with preferential transmission of the variant without insertion. When the sample of patients was stratified by sex and forms of schizophrenia, the significantly lower frequency of insertion was observed in the group of female patients with chronic schizophrenia (n=180) as compared to psychiatrically well women. The insertion variant has been reported earlier to be related to decreased levels of homocysteine and thus thought to play a protective role. In conclusion, our study revealed a possible relation of the CBS 844ins68 polymorphism to schizophrenia.