Evidence that HTR2A receptor gene may be subject to genomic imprinting prompted us to examine a collection of family trios for evidence of an association between the HTR2A T102C polymorphism and psychosis in schizophrenia or bipolar disorder. We also tested for the possibility of imprinting by employing quantitative RT-PCR to measure the relative expression of post-mortem brain mRNA for each allele in 45 subjects who were heterozygous for the T102C polymorphism. We found that the ratio of C102 to 102T allele mRNA expression was the same in major psychoses and healthy controls. There was no genetic association between HTR2A T102C with either schizophrenia or bipolar disorder under the assumption of a parent-of-origin effect, and these data together essentially exclude imprinting at this locus as a potential explanation for the complex inheritance observed in major psychoses.