This is the first study to examine the profile of mRNA expression of the dopamine D1, D2, D3, and D4 and serotonin 5-HT1A, 5-HT2A, and 5-HT3A receptors in PBMCs in medicated patients with schizophrenia, and to perform an in vitro analysis of the effects of six major antipsychotics on the receptor expression in PBMCs. The gene discussed is HTR2A; the disease is schizophrenia.