Several pieces of evidence implicate serotonin receptors in the aetiology of schizophrenia, and recently a number of studies have reported a genetic association between the 102T/C polymorphism of serotonin receptor type 2A gene and schizophrenia. Unfortunately a number of failures to replicate these positive associations in both Caucasian and Chinese populations have also been reported. We have examined the 102T/C polymorphism by PCR amplification and restriction analysis of DNA from: 202 schizophrenics and 202 controls from Shanghai; 112 schizophrenics and 224 parents from Chengdu, Cina; and 253 schizophrenics and 244 controls from the the UK. We find no evidence of association or transmission disequilibrium between the 102T/C polymorphism and schizophrenia in any of the groups we have examined. We conclude that either the original positive reports occurred by chance or any effect must be minimal, and urge caution in interpreting small positive results derived using data from different centres.