We studied the 5'-flanking promoter region comprising positions -1441 to +128 of the 5-HT2A receptor gene in 95 schizophrenics and 100 unrelated normal control subjects. The genes encoding the 5-HT2A receptor exons and the adjoining introl regions had already been studied in these subjects, but no disease specific polymorphism was found (Ishigaki et al., 1996). The DNA fragments were amplified by means of the polymerase chain reaction (PCR), and then analyzed by the single-stranded conformation polymorphism (SSCP) and sequencing methods. One patient had a substitution, from A to G, at position -668, and a 5 nucleotide deletion of TACTT at positions -646 to -642, however, the patient also had a normal sequence on the other allele. SSCP analysis showed that the other schizophrenics and the control subjects did not have any polymorphism in the 5'-flanking promoter region of the 5-HT2A receptor gene.